How to automatically delete idle client connections?

Dear community.

I would like to ask a question regarding the below error occurred when using psql client.
My environment is postgresql 12.3 docker container.
https://hub.docker.com/layers/postgres/library/postgres/12.3/images/sha256-23839ca029051ca19072dc7f40b252ae8cbcd7ef632f7b8e2da09ba3abc60214?context=explore

###
psql: error: could not connect to server: FATAL remaining connection slots are reserved for non-replication superuser connections
###

It seems that this is caused by unused psql client sessions. Which was caused by closing the terminal without exiting the psql session correctly.

###
postgres=# select usename,state,client_port from pg_stat_activity;
 usename  | state  | client_port
----------+--------+-------------
          |        |
 postgres |        |
 catseye  | idle   |          -1
 catseye  | idle   |       36718
 catseye  | idle   |          -1
 catseye  | idle   |       52960
 catseye  | idle   |       40854
...
###