There are two ways you can remove the ad from the edit box (blocking popups do not relevant to this as these are not pop ups):

1) After clicking the edit button and you see the form over the ad or the other way around hit the edit button again and you will be brought to an edit form on another page that doesn't have the ad.

2) A FT Premium account will eliminate all ads in the forums including these. More info: http://www.flyertalk.com/forum/claim_subscription.php

Thanks,