Hello,
I deleted two sections from a torus resulting in this open SubD (left). Then I inserted an edge loop as close as possible to each end (middle). Finally, I selected and deleted the narrow face loop from each end (right) but it didn’t work. As you can see, the newly inserted edge loops were deleted, but the open SubD is still the same length! Any advice?!
Face loops won’t delete.3dm (708.0 KB)
If you toggle to the boxy mode (tab-key), you’ll find that you have edge loops on top of each other. So when you remove the end faceloops you’ll end up with the same looking geometry because the next edgeloop is in the same location as the one you just removed.
Addendum:
In the screenshot above I moved an edge loop of the top pronge along the torus a bit using _Slide. Compare with the two edge loops that are on top of each other in the bottom pronge. Removing the edge loop at the top end now behaves probably along the lines you want
Thank you @nathanletwory 
Enjoy modelling with SubD in Rhino!
