Removing cork or polystyrene tiles is easy – you just lever them off the wall or ceiling with a large stripping knife. The problem is the adhesive they leave behind, that’s still firmly attached to the surface.
The best way to get rid of this is to soften it with an electric hot-air gun (also known as a hot-air stripper). It’s much safer than a blowtorch, because there’s no naked flame – it simply blasts hot air. Scrape the adhesive from the surface while it’s still soft, using the stripping knife.