Porcelain tile removal/replacement on foam backerboard

[old duffer]

I need to remove a few porcelain tiles that are fixed to a foam based tile backer-board.
Is it inevitable that I will have to cut and replace the foam board or is it possible to remove the tile from the board?
I ask because I've never done this before so need to know if its a method of going through the grout line and straight through the board and remove the tile and board.

 

[mrrusty]

If they were fixed properly, they won't come off the board. As you say, chop them out and re-board. Still might be tough if the boards are properly screwed.

 

[old duffer]

If they were fixed properly, they won't come off the board. As you say, chop them out and re-board. Still might be tough if the boards are properly screwed.

so the answer was to use a vibration saw to go through the grout gap and through the board and chop out whole tiles tiles.
What I had to do was take the tile next to it so as to expose a stud on which to fix the replacement backboard and then apply the tile again.