I have a curve through two points and tangency constraints at either end, with a tweak pulling out the curve a little more than the default. Now it's failed, and I need to redefine it. The tangency at one end has fallen off due to a surface being re-created. But it won't let me remove the tangency constraints until I remove the tweak. So how to I do that? I can change the tweak, but I don't know how to delete it alltogether.