I want to leave the Xbox inside program

You'll want to try posting over on the Insider Reddit to see if Insider staff can assist - https://www.reddit.com/r/xboxinsiders/

Open the Insiders app on your Xbox and make sure you're not a part of the Xbox Omega beta testing

Im pretty sure the app itself lets you know if you will have to factory reset, as far as I know It doesnt delete your games, but dont quote me on that,

What preview are you in?

Using the Insider hub >Manage should state what you're enrolled in.

Most of the time a factory refresh is required when leaving, changing a preview ring or leaving Insiders altogether. You will need the account details and passwords for all accounts that are set up on the console now to set the console back up after the factory refresh. Your games and apps shouldn't be affected unless you decide to do a complete factory refresh and delete everything. Xbox Insider FAQ

If you no longer wish to participate as an Xbox Insider and would like to unenroll your console from the program
you should remove it from the Xbox Insider Program by navigating to
Settings > Manage Devices, scrolling to your device marked
(current), selecting it and selecting Done.
After electing to remove a console, it may take up to 72 hours before the removal is complete, during which time you may still receive console, game, or app updates. As part of the removal process your console may undergo a factory refresh. If
a factory refresh is required, your games and apps will not be erased; however, any profiles or system settings saved to the console will need to be restored after the factory refresh is complete.