Log out a user and delete the account

First grep all the 'test' user's process and kill -9 all pid's then delete the user.

pgrep -u test
ps -fp $(pgrep -u test)
killall -KILL -u test
userdel -r test

passwd -l <user>

doesn't stop all possible means of logging in. For example, if they log in using ssh with public keys they can still login as they won't need a password.

To stop the user logging in again, edit the /etc/passwd file and remove the user or change the 7th column to /sbin/nologin.

Run:

ps -u <user>

to see what process the user is still using and kill them all of them. You may have to use:

kill -s 9 <pid>

to force the process to stop.

passwd -l <user> does not disable the account.as gareth said the user may still can login using another authentication token such as SSH key. to disable this account you should use usermod --expiredate 1 this set the account expire date to 1970. Now you should kill all processes the user is started. running:

$pgrep -u Foo will print all processes that the user Foo is started. running:

$kill -9 <pid> will sent SIGKILL signal which kill that process. Now Run:

$pgrep -u Foo | xargs kill -9

this will get all process ids of user Foo and kill them all.

OR:

$kill -9 -u Foo