Sigh. It's BETA and if you don't know how to downgrade, or can't google hoe to downgrade from a beta, you certainly shouldn't be running it to begin with.
Turn off your phone, plug it into your computer and simultaneously hold down home. iTunes will appear and then you choose upgrade and then iTunes will download the software and apply back the current released iOS version without requiring a full restore and your data will be intact. Make a backup before just in case.
Also I have a 6s plus and 9.1 is more stable than 9.0.2 was for me.