If you have a user account that you want to make unavailable, you can disable it. An account that has been disabled can be enabled again later. Disabling an account is different from deleting an account. If you delete an account, it can't be restored.
These steps cannot be completed on Windows Vista Starter, Windows Vista Home Basic, and Windows Vista Home Premium.
Open Microsoft Management Console by clicking the Start button , typing mmc into the Search box, and then pressing ENTER.
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
In the left pane of Microsoft Management Console, click Local Users and Groups.
If you don't see Local Users and Groups, it's probably because that snap-in has not been added to Microsoft Management Console. Follow these steps to add it:
In Microsoft Management Console, click the File menu, and then click Add/Remove Snap-in.
Click Local Users and Groups, and then click Add.
Click Local computer, and then click Finish.
Double-click the Users folder.
Right-click the user account you want to disable, and then click Properties.
On the General tab, select the Account is disabled check box, and then click OK.
To enable a disabled account, follow the same steps as you would for disabling an account, but clear the Account is disabled check box.