The pics show the roof gulley (after trim removed), the profile of the rubber insert (take care it goes back in the right way as it's not a symmetrical shape, my rubber coiled up and my freshly sprayed metal trim.
As per previous comments - it's easy to remove, with care, using a plastic tool and something to protect the paintwork you may contact.
The metal eases out from the rubber strip allowing the rubber to then be removed.
I did clean mine up before reinstalling.
I put my repainted metal strip into the rubber BEFORE putting the rubber back into the gulley. It presses in real easy, especially with some sort of slight lubrication.
Hope this helps.