Task: How to halt/stop user called linu

Type the skill command as follows:
# skill -STOP -u linu

You muse be root to stop other users.
Task: How to resume already halted user called linu

Send CONT single to user didi, type the following command:
# skill -CONT -u linu
Task: How to kill and logout user called linu

You can send KILL single, type the following command:
# skill -KILL -u linu
Task: Kill and logout all users

The ultimate command to kill and logout all users, type the following command:
# skill -KILL -v /dev/pts/*