How do I remove peeling paint from my bathroom wall before painting?

Get a lead testing kit to see if the paint contains lead. You can get this at Home Depot or Lowes.

If the wall or paint is in any way chipped or damaged, bubbling or peeling, then painting over it will not re-seal the lead paint. The toxins contained underneath all the layers will still be exposed through the topcoat, and therefore, always considered dangerous.

If you find yourself within a building that built prior to 1978 and the walls are in poor condition, then hiring a certified lead-paint removal team is important not only for the sake of the building’s integrity but also for the safety of everyone in the building

Wear a mask and use a hand sander to remove peeling paint and smooth out peeled edges. Wipe down and paint a coat or 2 of oil based primer, then paint what you want. Use moisture resistant top coat paint.

Scrape off what you can, then sand down the rough spots, paint Kilz on it and then paint your regular paint on it after it drys.

If there is lead in the paint don't touch it. You need pro's to remove and dispose of it properly. If there is no lead you can scrape off what is falling off. Then use 220 grit sandpaper to smooth it all out. Prime with Kilz primer then paint your color.