Delete guest account

I've had my MacBookAir two and half years now. I took it in to the shop for repairs two weeks ago and it came back with a log-in panel and a guest account. I hate it. How can I get rid of it.?

Thanks

Grace

Open System Preferences, Accounts. Open the small lock at the bottom of the dialog by authenticating with your Admin password, then uncheck both selections that say "Allow Guests......"

You may have to also highlight the Guest Account and click the small minus sign at the bottom. It should then say "Guest Account Disabled".

Regards.