Get Comfortable with the Downgrade Process
If you decide you want off the iOS 10.3.3 beta know that you'll only be able to go back to two versions of iOS 10: iOS 10.3.1 and iOS 10.3.2.
Apple recently stopped signing off on some its older iOS updates which means your only choice is to go back to one of these.
Apple will never close off the iOS 10.3.2 downgrade which means you will always be able to downgrade from iOS 10.3.3 beta to the current version of iOS 10.
It's important to get familiar with this downgrade process before you download the iOS 10.3.3 beta. If you feel leery about the process, you might be better off staying on an official version of iOS.