Required steps to rename user and home directory
Kill all processes owned by user and log him out
# pkill -9 -u old_usernameRename user from old_username to new_username
# usermod -l new_username old_usernameRename his home directory
# usermod -d /home/new_username -m new_usernameRename the primary group
# groupmod -n new_username old_usernameVerfiy the changes
# id new_username