doovalacky

A dremel will probably be the easiest cut the 45 off flush with the straight pipe. Then you have 2 options, carefully use one of the small cutting tips to partially cut thru the remaining 45 longwise and with a sharp screwdriver peel it off. Option 2 heatgun and warm up the top 2-3cm then push a piece of straight pipe into it once soft to make it a bell. ( Or a 45/90 female to male fitting rather than straight pipe) Baths have a lot of potential flow so I would be doing the joint...