Downgrade PMP 450i AP from to 16.1

Is it possible to downgrade a PMP 450i AP from to 16.1?
If possible is there a certain sequence to downgrade?

There are sometimes different hardware revisions. If your AP originally came with that old version - check the original event logs - you can downgrade. If it didn’t, it’s not guaranteed to work and an attempt may brick your AP.

Biggest question is - why do you want to do this downgrade?