Mark the section of backstitch (must be in backstitch mode), right click and select the erase option (I think it's the first option).
Alternate process - Select the arrow option and mark an area. Right click and select "erase area" to remove all stitches, including backstitches in the marked area. Any backstitch segments that extend beyond the marked area are not erased.
Just remember that if you use the auto or smart backstitch, you will have to tke out each line around each square. That is the only reason I do not like using it.
I agree with you. I can't go by the "estimate" of usage for backstitching because of it but since the backstitch is just for a visual reference for the pattern, the fact that it is 10 stitches long vs 1 stitch ling is not important. It is easier for me to use the longer stitches. It's also a lot easier (as you pointed out) to remove erroneous stitches!