postgresql error : ERROR: database is being accessed by other users

ERROR:  database "X" is being accessed by other users
DETAIL:  There is 1 other session using the database

Solution :

SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE pid <> pg_backend_pid() AND datname = 'database-name';

You need to replace only database name in above query.

Now you can drop the database or perform other activity what you were trying to perform.