As promised, Nokia Mobile published the Android Pie package for Nokia 8.1, so the users that opted to be part of the Android Q beta on Nokia 8.1 have the option to roll back to the previous, more stable version of Android OS and that’s Android 9 Pie.
If you opted for the beta and want to get out, now there is an option. The process is similar to installation and you have to go to Nokia Mobile’s developer portal to get the package. The process deletes data so be sure to back everything up. Techmesto has a great guide on this and you can check it here for more details.