How to remove window in mahogany front door without damaging

[dazzawazza]

Hi, one of the window panes in my mahogany front door has cracked. How do I remove the tacks in the wooden edging that holds the window in place without damaging the wood?
Or will I have to get new edging? If so where in London?

Also the treatment on the mahogany is beginning to fade. Is it most likely to be linseed oil, or is a different product used to treat mahogany?

Thanks