Removing a stovepipe connection

I have removed an old Franklin stove and stovepipe but the chimney and ceiling hardware are still in place and I'd like to remove the ceiling connection (I assume the chimney pipe may come out with it unfortunately). I can't figure out how the hardware that supports the chimney pipe is installed in the ceiling. I've looked at it in the attic and I don't see anything to unscrew. I've posted a photo and illustration at http://www.billrogers.net/photos/stovepipe
Thanks for any advice.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
crabshell wrote:

The large circular shim, I'll bet, is press-fitted to the pipe (same as a gas water heater flue).
Try wiggling the collar (maybe some WD40) and I'll bet the main pipe will slide out.
If push comes to shove, you should be able to Dremel-cut the collar off.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sounds reasonable. Now to figure out what to do with the hole in the roof...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.