One of the simplest methods for removing paint is to scrape it off with a flat-bladed putty knife. This is especially good for small corners and grooves.
There are a number of sanders you can use to remove paint from walls, but hand sanders with removable sanding pads are the most common. Larger belt sanders work well to remove paint from large horizontal surfaces.
You can also use wire brush attachments for a cordless drill to strip paint from walls and small spaces.
Heat guns, oriented more toward professionals, can be run over wall surfaces to melt away paint.
Paint strippers are liquid solvent-based paint removers that dissolve the bond between walls and paint when applied to walls.
Whenever you strip paint from walls or other surfaces, it is important to wear goggles to prevent any paint dust from getting in your eyes, and air masks to prevent the inhalation of any harmful lead or paint particles.