I have read your issue and I see that you still get install pop-ups from Anti-Theft software.
Please open the control panel and in the list check if you have an entry that says "Intel AT Service Signup", please select this service and uninstall it from your computer.
Please get back to us with the result after you do the above.
I presume the device is not enrolled with Anti-theft Service. You can disable the Pop-up at start up using the "msconfig" utility.
Open Run dialogue by pressing Win +R > type msconfig > OK
Click on the Start up Tab and scroll down to see if you find anything related to Anti-theft Sign up. Uncheck the checkbox and Click Apply.
Restart the computer to see if the pop-up disappears..!