It would be nice to add a feature within sketches that would undo fillets. When working with a 3D model its very simple to just delete the fillet feature, but when you are in sketches its a little more work. Typically I delete the fillet then coincident constrain the 2 points left. Depending on how the sketch is done, deleting the fillet can break constraints and dimensions. Same goes with chamfers. Could be added to the fillet drop down window.
