diff -u b/core/includes/config.inc b/core/includes/config.inc
--- b/core/includes/config.inc
+++ b/core/includes/config.inc
@@ -16,6 +16,22 @@
  */
 
 /**
+ * Uninstalls the default configuration of a given extension.
+ *
+ * @param string $type
+ *   The extension type; e.g., 'module' or 'theme'.
+ * @param string $name
+ *   The name of the module or theme to install default configuration for.
+ */
+function config_uninstall_default_config($type, $name) {
+  $storage = \Drupal::service('config.storage');
+  $config_names = $storage->listAll($name . '.');
+  foreach ($config_names as $config_name) {
+    \Drupal::config($config_name)->delete();
+  }
+}
+
+/**
  * Gets configuration object names starting with a given prefix.
  *
  * @see \Drupal\Core\Config\StorageInterface::listAll()
diff -u b/core/lib/Drupal/Core/Config/ConfigInstaller.php b/core/lib/Drupal/Core/Config/ConfigInstaller.php
--- b/core/lib/Drupal/Core/Config/ConfigInstaller.php
+++ b/core/lib/Drupal/Core/Config/ConfigInstaller.php
@@ -145,11 +145,2 @@
 
-  /**
-   * {@inheritdoc}
-   */
-  public function uninstallDefaultConfig($type, $name){
-    $config_names = $this->activeStorage->listAll($name . '.');
-    foreach ($config_names as $config_name) {
-      $this->configFactory->get($config_name)->delete();
-    }
-  }
 }
diff -u b/core/lib/Drupal/Core/Config/ConfigInstallerInterface.php b/core/lib/Drupal/Core/Config/ConfigInstallerInterface.php
--- b/core/lib/Drupal/Core/Config/ConfigInstallerInterface.php
+++ b/core/lib/Drupal/Core/Config/ConfigInstallerInterface.php
@@ -39,11 +39,2 @@
 
-  /**
-   * Uninstalls the default configuration of a given extension.
-   *
-   * @param string $type
-   *   The extension type; e.g., 'module' or 'theme'.
-   * @param string $name
-   *   The name of the module or theme to install default configuration for.
-   */
-  public function uninstallDefaultConfig($type, $name);
 }
diff -u b/core/lib/Drupal/Core/Extension/ModuleHandler.php b/core/lib/Drupal/Core/Extension/ModuleHandler.php
--- b/core/lib/Drupal/Core/Extension/ModuleHandler.php
+++ b/core/lib/Drupal/Core/Extension/ModuleHandler.php
@@ -724,7 +724,7 @@
       drupal_uninstall_schema($module);
 
       // Remove all configuration belonging to the module.
-      \Drupal::service('config.installer')->uninstallDefaultConfig('module', $module);
+      config_uninstall_default_config('module', $module);
 
       // Remove the module's entry from the config.
       $module_config->clear("enabled.$module")->save();