Toilet flange

[Indy]

Hey everyone. I’m trying to change the toilet flange on my2000 sun voyager Independence, and have discovered the flange is part of the down spout to the black tank.
Anyone know if it is glued to the tank, looks like a rubber connection, but I can’t get it loose.

Also is there an easier way than removing the water manifold?

[98sunvoyager]

Some flanges are threaded. I just found out by researching the same info as you.