Hide Filter in Sub category

here is my categories structure
main->sub1->sub2

i created menu of sub1 and selected direct sub elements in Sub elements filter,
it works for sub1 and hide filter,
but when i go inside sub2 , which actually includes products, filter comes again
I don't know why a simple thing is developed too complex, this should be very simple asking to show filter in menu or not, but it is not,
can anyone help regaring this?