First you need to gather all essential tools for demolition
You will need
- Protective gloves and goggles
- Dumpster or big bags
- Regular saw, jigsaw optional
- Hammer & chisel to remove tiles (best way to do it)
- Utility knife
- Whetstone for removing old mortar (use for thick layers wide chisel)
- Other tools & equipment for example warm air fan for drying moisture damage
First remove all items and fittings such as mirror, sink, toilet, thermostats etc. Take off old tiles with hammer and chisel. If tiles are on plasterboard it probably will break down. If you have chipboard it's possible to take tiles off with smaller damage but you still have to smooth it in preparation phase. In my case we also had to take down outer walls for drying it all out. Because this renovation is "temporary" for us, we didn't take all tiles off and did leave them on two main walls.
Remove tiles from floor and sand it with whetstone. After demolition clean everything up and vacuum dust. Be careful that you don't hit any pipes or electrical wires!