Hi
Perhaps you can find one or two small pieces of plastic (underneath) you can push back in untill the bracket can slide over and from the tubing.
Hope this helps, for I don't actually have Britax in stock.

If you look at the wheels from underneath.. at the bottom of where the grey stroller frame enters the wheel base... the black plastic juts out a bit on each side.. if you squeeze both sides, the wheel will come right off..