Hi,
AQ$__FT_Q_BEIN_I is an exception queue, you cannot drop exception queues, only normal queues.
In order to get the list of queues execute:

SELECT OWNER, NAME, QUEUE_TABLE
FROM DBA_QUEUES
WHERE OWNER = '&owner'
AND QUEUE_TYPE = 'NORMAL_QUEUE'
/

EXECUTE
DBMS_AQADM.STOP_QUEUE(QUEUE_NAME=>'the queue name');
DBMS_AQADM.DROP_QUEUE(QUEUE_NAME=>'the queue name');
DBMS_AQADM.DROP_QUEUE_TABLE(QUEUE_TABLE=>'the queue name');

Cheers.