ora-24005 must use dbms_aqadm.drop_queue_table

When you try to drop a user, you can encounter the following message :

ora-24005 must use dbms_aqadm.drop_queue_table

In some cases,   it's possible that you have tables with columns defined as SYS.ANYDATA .  In order to drop the user, you must first remove those aq_queue_tables ( any table which contains  this type is considered an aq_queue table ).

exec sys.dbms_AQADM.DROP_QUEUE_TABLE('USER.XXX',force=>true);