To remove a user from a Linux system, you can use the "userdel" command. This command will delete the user account and remove the user's home directory, as well as any other files and directories owned by the user.
For example, to remove the user "john", you can use the following command:
sudo userdel john
This will delete the user account and remove the user's home directory and other files.
If you want to keep the user's home directory and other files, you can use the "--remove" option to delete the user account but preserve the user's files. For example:
sudo userdel --remove john
This will delete the user account but leave the user's home directory and other files intact.
Note: Removing a user from the system will not affect any processes that the user has started. You may need to use other tools, such as "pkill" or "killall", to terminate the user's processes.