I had issues with 1903 and i was just wondering if i ever try it again i'd like to dual boot it with 1809, but when i'm done testing and i remove 1903 from my boot menu entries and delete the partition its on will windows still boot normally back into 1809? I know if i was using Windows 7 and i did this windows probably wouldn't as i'd have to repair the BCD? But i'm not sure how Windows 10 works .
Yes, You can, but if You remove one of them, then may be needed to repair something, it all depends how it was previously set up. But there is nothing insurmountable.Personally, I don't know any reason why you shouldn't be able to do it.