Hi, we had a gas central heating ststem installed and at the same time they added a shower which runs off the boiler too, that was 4 years ago and now we need to tile on the wall to which this is fastend to but can't seem to see how you would free it to push the tile under it or cutout the shape to fit under it, hope it makes sense, can anyone help?

A picture or brand and model of the mixing valve would help. Does your escutcheon look anything like this? Moen 16090 Chateau Escutcheon, Chateau 1 Handle Tub/Shower in Chrome