How to kill all open connections to POSTGRESQL using SQL command

 To close all existing connection to your database. We can pass the process/connection id to the predefined function pg_terminate_backend. Execute below query

SELECT 

    pg_terminate_backend(pid) 

FROM 

    pg_stat_activity 

WHERE 

    -- exclude current connection window

    pid <> pg_backend_pid()

    AND datname = '<database name>' 

Note: Database name is case sensitive