As with all beta programs, there are bound to be some bugs and issues that just aren't fun to deal with. If you've grown tired of testing the unfinished update, you can revert back to the latest official operating system for your device -- but heads up, you're likely going to have to set up your phone from scratch.
The first thing you'll need to do is download and install Samsung's Smart Switch program on a PC or Mac. The program is used to backup, sync and update software on Samsung's mobile devices. Download Smart Switch from Samsung's site.
After installing Smart Switch, open Samsung Members app on your mobile phone. In the app, tap Settings > One UI Beta Program > Deregister and follow the prompts.
With your device no longer enrolled in the beta program, it won't try to update to the beta after you roll back the operating system through Smart Switch.
Finally, open Smart Switch on your computer and connect your phone to your computer. The first screen of Smart Switch should display your device along with an Update button. Click Update and follow any prompts, which mainly consist of multiple warnings that your device will be factory reset during the update process and you should back up before resetting your phone.
Keep in mind that you won't be able to restore a backup created with the One UI Beta installed on your phone, so unless you created a backup before installing the beta, you will have to set up your phone as if it was brand new.
The entire process takes a while and is partly dependent on your connection speed to download the update to your computer, but once it's done, you'll no longer have to deal with any pesky bugs.