Hi Asad,
I think it is better to be careful and don't click that button by mistake, if you do click it by mistake then it shoould require either another Admin user who can unlock it or unlock it from the database for best security. It should be possible to lock any user. A company may have an employee who was an admin but left the company, it should be possible to lock that account. It would also be advisable to remove the account from the Admins role but that should not be required to lock an account.
Best,
Joe