I believe the Feedback Assistant is there on every Mac, beta or otherwise (at least, I’m not running the beta on my main Mac, yet it has the Feedback Assistant). Unenrolling will likely hide it from the Dock and Launchpad, but it can still be found at /System/Library/CoreServices/Applications/Feedback Assistant.app. You can manually symlink it to the /Applications folder to put it back in Launchpad or drag it straight to your Dock. But unenrolling should hide it from you.