After clearing grout out (use a sharp old knife if gap between tiles is small) to ensure you don't put any undue stress on surrounding tiles. To aid removing tile with small chisel or similar
put some masking tape on tile to be removed and drill smallish holes 5-7mm dia close together (tape prevents drill sliding about, alternative break tile surface finish with point of ceramic tile cutter to make drilling easy (surface below tile top surface will drill easily.
You will now have access to back of tile to gently remove tile pieces with out breaking surrounding tiles. You can also break tile into pieces using chisel to crack tile between drilled holes to aid removal without damage.
kibby
January 2006