Flat roof - Removal of old boiler vent stack

[larskaj]

Hi,
I have removed the old vent stack from a hot air boiler and I am left with the small piece that passes through the concrete flat roof.
It has lead flashing and is weather tight but I want to remove this piece and plug the hole.
This is the part I need help with, the plugging the hole.

 

[ree]

Why not ask the mods to transfer your post to the Roofing forum?

Close up pics would be better - the concrete seems to be covered with ply's of "felt"?