It means some session accessing that table. you can Query from v$access
Find that sid and kill that sid and drop the table
For sure there are locks, as the table is in use.
Drop table wants an exclusive lock on the corresponding dictionary record(s).
Whenever the table is in use there will be a row-share lock on that record in the dictionary.
Did you consult gv$access ?
Please do so now.
Senior Oracle DBA
Thanks alot for your help . gv$access resolved the issue .