The Linux Operating system is a multi-user operating system,( more number of users can work at a same time in network). Any user can able to login their user account in their desired system in a network. This arises a little security problem. To avoid such problems one can lock/disable their user account temporarily instead of deleting their user account.
To temporarily deactivate an account, disable their use’s password with the -l (lock) flag.
#passwd -l sathish
To re-enable, or unlock a user’s password use
#passwd -u sathish