Learn How to Downgrade
If you run into frustrating issues on the Android 10 beta, you can downgrade back to an official version of Android. Make sure you're comfortable with this process before you hit download.
Samsung's Beta FAQ goes over the downgrade process and it's worth a look if you've never tried a Galaxy beta update and/or you've never downgraded to another version of Android before.
The company says you'll be able to recover the data you backed up before the beta, but that "there may be limitations in recovering data that was created after installing the beta software."