I looked into this last night, the only way for me to remove them is to pay in forumotion credits to remove a large amount of the ads, almost all.
Also looked into forumotion prices, the thing to remove all ads for registered users is 1000 credits, which is about £8, and i'd rather not pay that for something so stupid, but if it gets really out of control, I will think about it,
Other then that, I think get a decent add blocker, should remove all adverts.
If your using chrome, click the wrench at the top, and go to tools, click it, extensions, browse the database, and type adblock into the left hand screen, in the search bar, download the first result, and add it to chrome, close of the guy asking for help, it's programmed into the thing.
Come back to BAA, and right click the advert, click the adblocker, and click to continue twice, should remove it, and make everything look nicer XD