how do i "waive my right recommendation"

my pre-college prof. told me that i should do the “waive my right recommendation” because colleges look at it more highly… how do i do that ?

i know it’s the FERPA waiver but do i HAVE to be 18

No, you don’t need to be 18. I waived the right and I am 17.
Basically when you go to the Recommenders and FERPA tab for any college, they’ll ask you to choose if you want to waive your right.