diff --git a/src/applications/oauthserver/storage/PhabricatorOAuthServerClient.php b/src/applications/oauthserver/storage/PhabricatorOAuthServerClient.php
--- a/src/applications/oauthserver/storage/PhabricatorOAuthServerClient.php
+++ b/src/applications/oauthserver/storage/PhabricatorOAuthServerClient.php
@@ -2,7 +2,9 @@
 
 final class PhabricatorOAuthServerClient
   extends PhabricatorOAuthServerDAO
-  implements PhabricatorPolicyInterface {
+  implements
+    PhabricatorPolicyInterface,
+    PhabricatorDestructibleInterface {
 
   protected $secret;
   protected $name;
@@ -89,4 +91,33 @@
     return null;
   }
 
+/* -(  PhabricatorDestructibleInterface  )----------------------------------- */
+
+  public function destroyObjectPermanently(
+    PhabricatorDestructionEngine $engine) {
+
+    $this->openTransaction();
+      $this->delete();
+
+      $authorizations = id(new PhabricatorOAuthClientAuthorization())
+        ->loadAllWhere('clientPHID = %s', $this->getPHID());
+      foreach ($authorizations as $authorization) {
+        $authorization->delete();
+      }
+
+      $tokens = id(new PhabricatorOAuthServerAccessToken())
+        ->loadAllWhere('clientPHID = %s', $this->getPHID());
+      foreach ($tokens as $token) {
+        $token->delete();
+      }
+
+      $codes = id(new PhabricatorOAuthServerAuthorizationCode())
+        ->loadAllWhere('clientPHID = %s', $this->getPHID());
+      foreach ($codes as $code) {
+        $code->delete();
+      }
+
+    $this->saveTransaction();
+
+  }
 }