Stains are the scourge of an otherwise clean house. However it got there, if you have a coffee stain tarnishing your wall's good image, you need something more substantial than a damp paper towel to remove the offending mark. Fortunately, removing even the stain of a dark French roast is an uncomplicated process. You also can take precautions to prevent any future caffeine-induced spills from staining your surfaces.
Spray the stain with a household cleaner and follow the instructions; some cleaners require a short amount of time to set in. If using a mild, non-spray detergent, work it into a soft-bristle brush with warm water to create suds.
Scrub the stain using a soft-bristle brush. Scrub from side-to-side in overlapping strokes for maximum effectiveness.
Wet and wring out a paper towel. Use it to wipe down the wall, rinsing away the cleaner and the stain.
Paint over any patches where the stain has become permanent. Use a roller and a semigloss, zero-VOC (volatile organic compound) paint that matches your wall. Paints like these not only cover your stain, but protect the wall against future mishaps.