Hi Ray,
The thing about having sfmSTO being positioned layout (because it is a leader subform) means that you can't add or remove rows within it, which is why the option is greyed out and the add/remove buttons are not working.
The delete button for the sfmReport should be working ... seems to work here.
My suggestion about moving sfmSTO under sfmReport is something I haven't tried but I think that will be the way you will need to go.
Regards
Bruce