If the adhesive is not cement based you could try sprinkling water to the wall to ease the scrapping process.
How to remove old tile adhesive from plaster wall.
Wait several minutes and use a large scrapper to remove the mastic.
Since not all will come off there will be an uneven layer of adhesive left behind.
If any adhesive gets stuck to the brush remove it by hand and continue until no more adhesive remains on the wall.
I have started by removing the tiles from the walls but the plasterboard is now a mess with patches lumps of tile adhesive still stuck to it.
You will then have to pry off the leftover residue.
If the adhesive used was organic mastic the water will begin to soften it allowing you to.
How to remove ceramic tile glue from a wall.
Apply an adhesive removing paste to the wall.
Apply some water to a small section of the adhesive.
Irrespective of the adhesive formula you have to cover the floor with old cloths as to protect it from the residues which will fall off the wall.
All the the tiles have been removed by bolster chisel and as you will all know the bare plasterboard is now a mess and i need it to be clean before i can start putting the new tiles up.
Step 3 wipe some tile adhesive remover over the surface of the wall.
Scrape the surface of the adhesive with a stiff bristle brush.