FontLab’s Merge Contours works fine, but the Intersection operations really bite. Personally, I prefer CorelDraw's straightforward approach: Weld (merge or union), Trim (delete intersection or minus front/back) and Intersection (get), all with the options of leaving or deleting the source and target objects.
Consequently, in CorelDraw, if you selected Trim/Delete Source/Delete Target, what you would end up with is the just the upright in your example, properly “minused.” As it is, you will need to use the Wand Tool to select your trim source and cut or delete it, then use the tool to select the intersection and delete it, then select all and use Merge Contours to clean up any mess let behind.