You need to send an email to members@wgt.com giving the username of this player.
I have seen a few lately in my country club and reported them to WGT.
The person I reported is still a member though. Typical WGT. It was obvious from the scores they were shooting with starter equipment after less than a month, that they were a multi-accounter. Basically they learn the game under one account, then create another account (hack) and play people with the advantage of the shorter hole distance.
Multi-Accounters are a pain. Basically if you are going to play someone for credits, go check out their page. See how long they are a member and what sort of scores they are shooting. If they look dodgy, don't play them