dropdb: database removal failed: ERROR: database "database_name" is being accessed by other users - Mailing list pgsql-admin

This Error message was given when i was dropping the database.
There are idle connections to the database as seen from ps -ef | grep postgres

How can i drop the database with out restarting the postgres server.?.

FYI: i am dropping the database to perform restoration of this backup
database using psql  from production.

--
Best,
Gourish Singbal