Start by removing any molding switch plates outlet covers and other hardware attached to the area being tiled.
How to dry out wall behind tiles.
All tiles need to be removed from shower area walls inspected for moisture penetration mould.
Turn the float to 90 degrees to remove the excess grout from the tile faces.
If they are solid walls then allowed to dry out and once dried sealed with sbr primer ready for re tiling.
If plaster board is behind tiles then this should be removed and replaced with cement board which will not absorb moisture like plaster board.
Tap a rubber mallet on the head of a small chisel to remove the grout in the tile joints.
Its quite an old flat c1900.
Use the rubber mallet to tap the head of the putty knife to pop the ceramic tile from its place.
I am running a fan for a few more days to try to dry out behind the tile.
Step 2 place a wide putty knife under the ceramic tile parallel to the floor.
Let the wall dry thoroughly.
You want the tile adhesive to have something to grab onto.
Thoroughly vacuum the area and give the wall a once over with a damp sponge or cleaning cloth.
Remove any remaining dust oil or grease with tsp tri sodium phosphate or an ammonia based cleanser.
You then need to remove the damp air.
Not sure how long it will take to dry the wall out any.
Hold the float at a 45 degree angle to the wall to push the grout into the joints between the tiles.
A fan inside the cube will dry the water out of the wall.
However remember you must not have portable electrical appliances in a bathroom.
The corners have little grout after removing the caulk they have up to 1 8 gaps up to the top of the shower.
Let the grout dry.
Seal the walls with a skim coat and let it dry thoroughly.
The tile is 12 floor tile w inlay tiles.
An extractor or a dehumidifier or good airflow which includes the window plus another point of entry would do.