If you have a bench vise available, that's better than using a wrench to try to loosen the freewheel. Attached the remover tool with the QR, clamp the flats of the tool in the vise, turn the wheel in the correct direction (clockwise: the opposite direction to how the chain would normally pull!). Using a vise applies more even torgue than a wrench. If the QR is tight enough, the remover tool shouldn't derail, as long as its notches are intact. If the remover tool's notches are mangled, get another tool.

If you still have no luck, then yes, consider destructive removal.