1) Make sure all of the users processes are dead.

ps -u username

^will show you everything that user is running. Then to kill all of their processes:

ps -ef | grep admin | awk ‘{ print $2 }’ | xargs kill -9

(or you can su to them and run “kill -9 -1?)

2) Obviously as root, run the following:

usermod -u NEWUID username

3) Or, you could just edit passwd.

4) Either way, profit!

Helped from here.

Mario Loria is a builder of diverse infrastructure with modern workloads on both bare-metal and cloud platforms. He's traversed roles in system administration, network engineering, and DevOps. You can learn more about him here.