I want out of the preview program.

What should I do if I want to stop participating in the program?
If you decide that you don't want to get Preview updates anymore you can opt out in the Xbox Preview Dashboard app. You won't be removed from the program right away; it won't happen until the current update is released to the general public. If you change
your mind, you can always re-register your console later using the Xbox Preview Dashboard app.

Here's how to remove your console from the Xbox Preview program:

1. Open the Xbox Preview Dashboard app.
2. Select Registration.
3. Under Manage flights, select Change.
   
   Note If you have more than one console in the program, you can change their statuses by using Manage other consoles.
4. Under Manage programs, select Remove, and then select Submit. You'll be prompted to select a reason for leaving.

If you run into any issues, post in the private Xbox Early Access forums for help.

Note Your console won't be removed from the program until the current Preview update is released to the general public, so it won't happen right away. Until then, your console's status will show as Pending.

LINK

As i said previous ReepinKilla2

It's recommended that players who aren't familiar with development shouldn't go into those settings it is possible that it can mess some stuff up with the console rendering it useless until repairs are done to it.

to all that are having a problem with the latest preview release and EA games not working anymore, the fix is real simple. go to settings system update and press LB,RB,LT,RT at the same time to bring up dev mode. click on reset home console and restart you
xbox. now boot up an EA title back out to the dashboard press the menu button to quit the game and then make your xbox your home console again and VOILA. I take claim for this workaround.

To Opt out off Preview start up th XBOX preview dashboard then go to registrastion and remove your xbox from the programme after the new update rolls out to the public youll be opted out

Also to add, opting out of the program will not immediately remove you from the program. Once the current build is released to the public, you will be removed.