Hi,
If you look at the script in the reset button here: https://acrobat.com/#d=RZ1lzX23*u7L4N9rtWCYPQ
You will see that it has a 'while' loop that keeps deleting instances until it gets down to the minimum of two.
while (flowedSubform.Table1._Row1.count > 2)
{
flowedSubform.Table1._Row1.removeInstance(1);
}
A similar approach would work for repeating subforms.
Good luck,
Niall
PS: Note the underscore in front of the repeatable object "_Row1" is shorthand for "instanceManager".