Thanks for logging in on this, Jim. I tried your suggestion on an
unprotected sheet, and am still having the issue with the error
seemingly not getting trapped - NO message is displayed when I hit ESC
while Subtotals are being removed - the process just stops with a beep,
the Data Outline has been removed but the subtotals rows are still
there.

If it helps advance this issue, I would be glad to email a file I am
using with enough Subtotals to allow time to hit ESC (i.e., to allow
experimenting). I have been struggling with this issue for 2+ days ...
and just seem to be going around in circles ...

Jeff