diff --git a/HISTORY.rst b/HISTORY.rst
index 17a8786b..538649fa 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -30,8 +30,8 @@ PlatformIO Core 4
   - Built-in fine-grained access control (role based, teams, organizations)
   - Command Line Interface:
 
-    * `platformio package publish <https://docs.platformio.org/page/core/userguide/package/cmd_publish.html>`__ – publish a personal or organization package
-    * `platformio package unpublish <https://docs.platformio.org/page/core/userguide/package/cmd_unpublish.html>`__ – remove a pushed package from the registry
+    * `pio package publish <https://docs.platformio.org/page/core/userguide/package/cmd_publish.html>`__ – publish a personal or organization package
+    * `pio package unpublish <https://docs.platformio.org/page/core/userguide/package/cmd_unpublish.html>`__ – remove a pushed package from the registry
     * Grant package access to the team members or maintainers
 
 * New **Package Management System**
@@ -46,7 +46,7 @@ PlatformIO Core 4
   - Command launcher with own arguments
   - Launch command with custom options declared in `"platformio.ini" <https://docs.platformio.org/page/projectconf.html>`__
   - Python callback as a target (use the power of Python interpreter and PlatformIO Build API)
-  - List available project targets (including dev-platform specific and custom targets) with a new `platformio run --list-targets <https://docs.platformio.org/page/core/userguide/cmd_run.html#cmdoption-platformio-run-list-targets>`__ command (`issue #3544 <https://github.com/platformio/platformio-core/issues/3544>`_)
+  - List available project targets (including dev-platform specific and custom targets) with a new `pio run --list-targets <https://docs.platformio.org/page/core/userguide/cmd_run.html#cmdoption-platformio-run-list-targets>`__ command (`issue #3544 <https://github.com/platformio/platformio-core/issues/3544>`_)
 
 * **PlatformIO Build System**
 
@@ -58,12 +58,13 @@ PlatformIO Core 4
 
 * **Miscellaneous**
 
-  - Display system-wide information using a new `platformio system info <https://docs.platformio.org/page/core/userguide/system/cmd_info.html>`__ command (`issue #3521 <https://github.com/platformio/platformio-core/issues/3521>`_)
-  - Dump data intended for IDE extensions/plugins using a new `platformio project idedata <https://docs.platformio.org/page/core/userguide/project/cmd_idedata.html>`__ command
-  - Added a new ``-e, --environment`` option to `platformio project init <https://docs.platformio.org/page/core/userguide/project/cmd_init.html#cmdoption-platformio-project-init-e>`__ command that helps to update a PlatformIO project using existing environment
-  - Added support for "globstar/`**`" (recursive) pattern for the different commands and configuration options (`platformio ci <https://docs.platformio.org/page/core/userguide/cmd_ci.html>`__, `src_filter <https://docs.platformio.org/page/projectconf/section_env_build.html#src-filter>`__, `check_patterns <https://docs.platformio.org/page/projectconf/section_env_check.html#check-patterns>`__, `library.json > srcFilter <https://docs.platformio.org/page/librarymanager/config.html#srcfilter>`__). Python 3.5+ is required.
-  - Do not generate ".travis.yml" for a new project, let the user have a choice
+  - Display system-wide information using a new `pio system info <https://docs.platformio.org/page/core/userguide/system/cmd_info.html>`__ command (`issue #3521 <https://github.com/platformio/platformio-core/issues/3521>`_)
+  - Remove unused data using a new `pio system prune <https://docs.platformio.org/page/core/userguide/system/cmd_prune.html>`__ command (`issue #3522 <https://github.com/platformio/platformio-core/issues/3522>`_)
+  - Dump data intended for IDE extensions/plugins using a new `pio project idedata <https://docs.platformio.org/page/core/userguide/project/cmd_idedata.html>`__ command
+  - Added a new ``-e, --environment`` option to `pio project init <https://docs.platformio.org/page/core/userguide/project/cmd_init.html#cmdoption-platformio-project-init-e>`__ command that helps to update a PlatformIO project using existing environment
+  - Added support for "globstar/`**`" (recursive) pattern for the different commands and configuration options (`pio ci <https://docs.platformio.org/page/core/userguide/cmd_ci.html>`__, `src_filter <https://docs.platformio.org/page/projectconf/section_env_build.html#src-filter>`__, `check_patterns <https://docs.platformio.org/page/projectconf/section_env_check.html#check-patterns>`__, `library.json > srcFilter <https://docs.platformio.org/page/librarymanager/config.html#srcfilter>`__). Python 3.5+ is required.
   - Updated PIO Unit Testing support for Mbed framework. Added compatibility with Mbed OS 6
+  - Do not generate ".travis.yml" for a new project, let the user have a choice
   - Do not escape compiler arguments in VSCode template on Windows
   - Fixed an issue with PIO Unit Testing when running multiple environments (`issue #3523 <https://github.com/platformio/platformio-core/issues/3523>`_)
 
diff --git a/docs b/docs
index d01bbede..be04ee45 160000
--- a/docs
+++ b/docs
@@ -1 +1 @@
-Subproject commit d01bbede6ca90420ed24736be4963a48228eff42
+Subproject commit be04ee45c8d037c8eecbbe9a178926593fd620a0
diff --git a/platformio/commands/system/command.py b/platformio/commands/system/command.py
index 2fee5471..cb311205 100644
--- a/platformio/commands/system/command.py
+++ b/platformio/commands/system/command.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import json
+import os
 import platform
 import subprocess
 import sys
@@ -20,7 +21,7 @@ import sys
 import click
 from tabulate import tabulate
 
-from platformio import __version__, compat, proc, util
+from platformio import __version__, compat, fs, proc, util
 from platformio.commands.system.completion import (
     get_completion_install_path,
     install_completion_code,
@@ -30,6 +31,7 @@ from platformio.package.manager.library import LibraryPackageManager
 from platformio.package.manager.platform import PlatformPackageManager
 from platformio.package.manager.tool import ToolPackageManager
 from platformio.project.config import ProjectConfig
+from platformio.project.helpers import get_project_cache_dir
 
 
 @click.group("system", short_help="Miscellaneous system commands")
@@ -95,6 +97,27 @@ def system_info(json_output):
     )
 
 
+@cli.command("prune", short_help="Remove unused data")
+@click.option("--force", "-f", is_flag=True, help="Do not prompt for confirmation")
+def system_prune(force):
+    click.secho("WARNING! This will remove:", fg="yellow")
+    click.echo(" - cached API requests")
+    click.echo(" - cached package downloads")
+    click.echo(" - temporary data")
+    if not force:
+        click.confirm("Do you want to continue?", abort=True)
+
+    reclaimed_total = 0
+    cache_dir = get_project_cache_dir()
+    if os.path.isdir(cache_dir):
+        reclaimed_total += fs.calculate_folder_size(cache_dir)
+        fs.rmtree(cache_dir)
+
+    click.secho(
+        "Total reclaimed space: %s" % fs.humanize_file_size(reclaimed_total), fg="green"
+    )
+
+
 @cli.group("completion", short_help="Shell completion support")
 def completion():
     # pylint: disable=import-error,import-outside-toplevel
diff --git a/platformio/fs.py b/platformio/fs.py
index 75bf959c..da2101c5 100644
--- a/platformio/fs.py
+++ b/platformio/fs.py
@@ -85,6 +85,17 @@ def calculate_file_hashsum(algorithm, path):
     return h.hexdigest()
 
 
+def calculate_folder_size(path):
+    assert os.path.isdir(path)
+    result = 0
+    for root, __, files in os.walk(path):
+        for f in files:
+            file_path = os.path.join(root, f)
+            if not os.path.islink(file_path):
+                result += os.path.getsize(file_path)
+    return result
+
+
 def ensure_udev_rules():
     from platformio.util import get_systype  # pylint: disable=import-outside-toplevel