i ve had some luck by just attempting to "BREAK THE BEAD" like you would a normal tire. start by slowly working the tire off the rim edge..and just keep pushing adn working around the rim...in tough cases, i have used a new exacto knife to CAREFULLY trim the glue seal from the tire and rim, take care and use caution so you dont take your thumbs off with the tire. with care you can get the tire off without loosing a digit from your hand, AND have a usable tires to boot.
tim