public static void revoke(Connection connection, final String namespace, final String userName,
    final Permission.Action... actions) throws Throwable {
    connection.getAdmin().revoke(
      new UserPermission(userName, Permission.newBuilder(namespace).withActions(actions).build()));
  }
Revokes the permission on the namespace for the specified user.
@param connection The Connection instance to use
hbase-client/src/main/java/org/apache/hadoop/hbase/security/access/AccessControlClient.java