I want to leave the xbox insider

My console doesn't appear there but states it's in the program. I didn't use my account to add it. Is that why?

Thats Correct. The account that enrolled your console into the program would need to login to remove that console from the program.

Go into the Insider Hub app and side scroll to the settings section, then Manage Devices, and de-authorize the console from the program. Keep in mind, this will remove you from the program and also remove all Insider updates. As such, your console can
auto default back to its original settings which is the same thing as doing a complete factory reset. You will need to re-install your account and all digital content onto the console once you boot it back up. When I left, it took a few days before the console
reverted itself back to factory defaults. Good luck!

My console doesn't appear there but states it's in the program. I didn't use my account to add it. Is that why?

Go into the Insider Hub app and side scroll to the settings section, then Manage Devices, and de-authorize the console from the program. Keep in mind, this will remove you from the program and also remove all Insider updates. As such, your console can
auto default back to its original settings which is the same thing as doing a complete factory reset. You will need to re-install your account and all digital content onto the console once you boot it back up. When I left, it took a few days before the console
reverted itself back to factory defaults. Good luck!

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