Normally, we first w first, then pkill -kill -t pts/1 (pts/1 is the user terminal number seen by the w command), and we can kick the user, but there is a situation where we can't kick it, that is, the user is Using SSH to jump to other servers, he did not log in directly to ssh.
Memo -. -
[root@jump ~]# userdel ly
userdel: user ly is currently used by process 19789
[root@jump ~]# ps -ef|grep ly
root 19787 2868 0 14:48 ? 00:00:00 sshd: ly [priv]
ly 19789 19787 0 14:48 ? 00:00:00 sshd: ly
root 20134 18680 0 15:00 pts/4 00:00:00 grep ly
[root@jump ~]# kill 19787 2868 19789
[root@jump ~]# ps -ef|grep ly
root 20160 18680 0 15:00 pts/4 00:00:00 grep ly
[root@jump ~]# userdel -r ly