I do this on a regular basis for students & for myself.

As to how much dihedral to remove -- it depends upon what you want the model to do. If it is a trainer type & you want to max its aerobatic capability, you may not only want to remove all of the dihedral, you may want to introduce anhedral &/or cut the wing down into the cabin, to bring the center of lift closer to the thrust line.

The more you take out, the closer to a point-&-shoot airframe you will get -- and the less auto-recovery it will have. A full-out mod will take constant flying (no hands off), but it will be rewarding flying.