Is it possible to remove Beta software from Edge 1040?

I subscribed to the current Beta programme for Edge 1040, which gives the functionality of the new 1050 and the device has become almost unworkable. It's freezing on the map screen when following a route, not showing vehicles approaching from the connected Varia radar (but is counting the vehicles as they pass and so I know the 1040 sees them), regularly saying I am off route when I'm not, Climb pro starting a climb a good 100 metres after the climb started. Etc.... 

I hadn't realised the Beta software would be so buggy it would make using the device almost unusable.

I've withdrawn from the Beta programmme, but the website says it will now leave me on the current Beta version and will only update when the final version is released to public.

I'd like to go back to a previous firmware that works better. Is this possible?

Thanks for any help.