Linux command for username and group

Change or rename user name and UID (user-id)
# usermod -l <new_username> <old_username>
# usermod -u UID <username>

List username from a group

# getent group <groupname>

Remove username from a group

# gpasswd -d <username> <group>

Remove/Delete a user account

# userdel <username>

The following command will also remove user home directory

# userdel -r <username>

Add user to a group

# adduser <username> <group>