diff --git a/src/Forms/HTMLEditor/HTMLEditorConfig.php b/src/Forms/HTMLEditor/HTMLEditorConfig.php
index 10b59959a..50a5124a8 100644
--- a/src/Forms/HTMLEditor/HTMLEditorConfig.php
+++ b/src/Forms/HTMLEditor/HTMLEditorConfig.php
@@ -80,15 +80,19 @@ abstract class HTMLEditorConfig
     }
 
     /**
-     * Assign a new config for the given identifier
+     * Assign a new config, or clear existing, for the given identifier
      *
      * @param string $identifier A specific identifier
-     * @param HTMLEditorConfig $config
+     * @param HTMLEditorConfig $config Config to set, or null to clear
      * @return HTMLEditorConfig The assigned config
      */
-    public static function set_config($identifier, HTMLEditorConfig $config)
+    public static function set_config($identifier, HTMLEditorConfig $config = null)
     {
-        self::$configs[$identifier] = $config;
+        if ($config) {
+            self::$configs[$identifier] = $config;
+        } else {
+            unset(self::$configs[$identifier]);
+        }
         return $config;
     }
 
diff --git a/src/Forms/HTMLEditor/TinyMCECombinedGenerator.php b/src/Forms/HTMLEditor/TinyMCECombinedGenerator.php
index ace718319..90fb5c116 100644
--- a/src/Forms/HTMLEditor/TinyMCECombinedGenerator.php
+++ b/src/Forms/HTMLEditor/TinyMCECombinedGenerator.php
@@ -6,14 +6,17 @@ use SilverStripe\Assets\Storage\GeneratedAssetHandler;
 use SilverStripe\Control\Director;
 use SilverStripe\Core\Config\Configurable;
 use SilverStripe\Core\Convert;
+use SilverStripe\Core\Flushable;
+use SilverStripe\Core\Injector\Injectable;
 
 /**
  * Generates tinymce config using a combined file generated via a standard
  * SilverStripe {@link GeneratedAssetHandler}
  */
-class TinyMCECombinedGenerator implements TinyMCEScriptGenerator
+class TinyMCECombinedGenerator implements TinyMCEScriptGenerator, Flushable
 {
     use Configurable;
+    use Injectable;
 
     /**
      * Named config
@@ -201,4 +204,17 @@ class TinyMCECombinedGenerator implements TinyMCEScriptGenerator
         );
         return $url;
     }
+
+    /**
+     * This function is triggered early in the request if the "flush" query
+     * parameter has been set. Each class that implements Flushable implements
+     * this function which looks after it's own specific flushing functionality.
+     *
+     * @see FlushMiddleware
+     */
+    public static function flush()
+    {
+        $dir = dirname(static::config()->get('filename_base'));
+        static::singleton()->getAssetHandler()->removeContent($dir);
+    }
 }
diff --git a/tests/php/Forms/HTMLEditor/TinyMCECombinedGeneratorTest.php b/tests/php/Forms/HTMLEditor/TinyMCECombinedGeneratorTest.php
index 46ceed868..ff47b8514 100644
--- a/tests/php/Forms/HTMLEditor/TinyMCECombinedGeneratorTest.php
+++ b/tests/php/Forms/HTMLEditor/TinyMCECombinedGeneratorTest.php
@@ -19,10 +19,17 @@ class TinyMCECombinedGeneratorTest extends SapphireTest
         // Set custom base_path for tinymce
         Director::config()->set('alternate_base_folder', __DIR__ . '/TinyMCECombinedGeneratorTest');
         Director::config()->set('alternate_base_url', 'http://www.mysite.com/basedir/');
-        SSViewer::config()->set('themes', [ SSViewer::DEFAULT_THEME ]);
+        SSViewer::config()->set('themes', [SSViewer::DEFAULT_THEME]);
         TinyMCEConfig::config()->set('base_dir', 'tinymce');
     }
 
+    protected function tearDown()
+    {
+        parent::tearDown();
+        // Flush test configs
+        HTMLEditorConfig::set_config('testconfig', null);
+    }
+
     public function testConfig()
     {
         // Disable nonces
@@ -83,4 +90,28 @@ EOS
             $content
         );
     }
+
+    public function testFlush()
+    {
+        // Disable nonces
+        $c = new TinyMCEConfig();
+        $c->setTheme('testtheme');
+        $c->setOption('language', 'en');
+        $c->disablePlugins('table', 'emoticons', 'paste', 'code', 'link', 'importcss');
+        $c->enablePlugins(['plugin1' => 'mycode/plugin1.js']);
+        HTMLEditorConfig::set_config('testconfig', $c);
+
+        // Generate file for this
+        /** @var TinyMCECombinedGenerator $generator */
+        $generator = Injector::inst()->create(TinyMCECombinedGenerator::class);
+        $generator->getScriptURL($c);
+        $filename = $generator->generateFilename($c);
+
+        // Ensure content exists
+        $this->assertNotEmpty($generator->getAssetHandler()->getContent($filename));
+
+        // Flush should destroy this
+        TinyMCECombinedGenerator::flush();
+        $this->assertEmpty($generator->getAssetHandler()->getContent($filename));
+    }
 }