How to remove this 6"-3" adapter?

[MwCrf450r]

So I have a wood stove in the basement and a pellet stove upstairs. I want to swap them. Unfortunately I can't figure out how to remove this adapter? Any advice?

 

[MwCrf450r]

I can spin it but doesn't seen to want to come loose. Have I just not found the sweet spot yet? I can feel any screws

 

[kchace]

When you say you can spin it, are you spinning the 3” part Only? That adapter looks like it is stuck into a larger pipe. It should come out right at the edge where it goes to 6”.

 

[MwCrf450r]

When you say you can spin it, are you spinning the 3” part Only? That adapter looks like it is stuck into a larger pipe. It should come out right at the edge where it goes to 6”.

I got it. It was glued into a 6" piece then glued into the flue. That flexible rubber stuff holds pretty stinkin well lol