Unable to remove elements from form Design List

Question

I've made a form in AX 2012 and duplicated, renamed and deleted countless elements in the Form Design.

I now have many elements in my Design List that are no longer in my form's design (CopyOfGrid2_Payment, CopyOfGrid2_SalesId ect..), but I am unable to remove/delete them: no right click delete or delete key on the keyboard.

Any ideas how I can get rid of elements in my Design list that are not part of the Design? Any ideas why I am not able to delete these elements?

Answer 1

The fields are included in a field group and the group included in the form.