[edit] How to remove you cranks, when you have already stripped the removal thread.

Right, this has happened a lot of times, in trials, your cranks need to be super tight, so when it comes to taking them off, you run the chance of stripping the thread. The old method at this point is to decide whether to save your crank, or bb, and then reach for the angle grinder.

All you need to do is to buy a 3 leg flywheel puller, designed for pulling the flywheel off a motorbike engine, then you need to get a big bolt and cut the head down, it needs to be big enough to cover the end of the BB, but not touch the crank.

This is the bolt.

Apply the bolt and the puller as shown below, and tighten up until the crank comes off.