Unfortunately, please refer to the following thread.
Sorry but there is no support for anti theft if you do not remember the password you are stuck.
Shera Noor wrote:
Please can u help me..my laptop was locked by anti theft service. Where i can get my user password. Ty so much.
McAfee Support does not have access to your password.
If your device is locked you may be able to retrieve your unlock password through the Anti-Theft web portal through the expired subscriptions link on the subscription page of My Account. The ability to unlock your device remains unchanged; you will need to enter your 8 character unlock password. If you are unable to remember or recover your unlock password, the Anti-Theft service will follow its design and lock the device. At this point, your only option would be to contact your computer’s manufacturer to request service - in most cases this means replacing the motherboard.