Deleting a fillet, a chamfer or anything else by selecting its surface(s) and pressing Del is very helpful. Yet very often with complex shapes, one has to find the right combination of surfaces to select to have the feature working.
When the amount of surfaces becomes great enough, it gets rapidly quite a pain having to re-select all the surfaces +1.
A solution that might be easy to implement would be to keep the surfaces (or anything else previously selected) still selected, event if the feature Delete has failed. That way, one could just add or remove one or several surfaces and pursue their quest of the Rightful Surface Deleting Combination.
Cheers!