Only way is to restore with itunes.
9.3.3 is the latest ios version and still signed by Apple.
Instead of looking to jump through 100 hoops just plug it in and restore it. You might not be able to do it for too long so you should do it while you still can.
As long as ios 9.3.3 is still signed then you could downgrade from beta or from any version you want.
Once 9.3.3 stops being signed by Apple you can never restore to that version. Doesn't matter if you're on ios 10, or on a beta or ios 20.