Mark D Powell wrote:the OP not helping us to know what he did , what the changes that he made , but i am with harry that restart database maybe will solve the issue and the OP must learn how to trouble shoot Not Delete DBA_users this the most strange thing i ever heard today.
Harry's reply made me thing of something you can try. Generate the drop for and drop all the user objects then try to alter user x account lock.
This would prevent the account from being used till you can bounce the database instance and then retry the drop user.
HTH -- Mark D Powell --