I've taken out a few, and it's a wear eye protection job, in fact all jobs that can give off flying splinters is an eye protection job so remember that and you wont suffer injury. Oh! gloves as well and hard hat for work above head height [does it show I was in charge of my works safety].
On most there are four metal tabs [two each side] down the side edges of the surrounds approx 6ins from top and 8-9 from bottom, they are the fixing points. chase out a channel down each side to locate these tabs and prise them away, there maybe two at the top. It also helps to use wood wedges as you pull away the surround put a wedge in the gap so your crowbar can get better purchase behind the surround.
Alternative is to grind through the tabs with an angle grinder using of course a metal cutting disc. Again WEAR eyeshields.
Mask the edges of the wood surround before making good the plaster its a bugger trying to get plaster stains off the timber.
Rob
July 2007