title: Can't revoke default schema privilege
body: <p>pgadmin shows the default privilege for a schema was granted to an individual user and I need to revoke privilege granted from individual users.</p>
  <pre><code>ALTER DEFAULT PRIVILEGES IN SCHEMA a_schema
   GRANT ALL ON TABLES TO a_user;
  </code></pre>
  <p>I try the following command but can't revoke the privilege.</p>
  <pre><code>ALTER DEFAULT PRIVILEGES IN SCHEMA a_schema
   REVOKE ALL ON TABLES FROM a_user;
  </code></pre>
  <p>Can someone show me how to revoke the default privilege schema from user?</p>