To mark database ‘applogs’ as not accepting new connections:
update pg_database set datallowconn = false where datname="applogs";
Another possibility would be to revoke ‘connect’ access on the database for the client role(s).
Disconnect users from database = kill backend. So to disconnect all other users from “applogs” database, for example:
select pg_terminate_backend(procpid)
from pg_stat_activity
where datname="applogs" and procpid <> pg_backend_pid();
Once you’ve done both of those, you are the only user connected to ‘applogs’. Although there might actually be a delay before the backends actually finish disconnecting?