I've had this problem while computers were domain joined before but never on a solo computer. There are now settings for IT admins to control windows insider programs on computers via group policy. gpedit.msc will allow you to open up your local machine policy and make changes to it if you have admin credentials.
I have the same problem but obviously nobody from MS was kind enough yet to post a reply on how to solve this problem. After all, I am the "organization" that manages Group Policy settings but NOT through telemetry as the Settings window claims. Where can I change these Group Policy settings? I never set them!