To remove Sellotape residue, apply rubbing alcohol to the spot and let it sit for several minutes. After letting it sit, wipe the residue away with a cloth or paper towel.
Another way to remove the residue of Sellotape, which is a transparent adhesive tape available in Great Britain, is to heat up an iron and place it close to the spot without touching it, or getting it close enough to burn it. Hold the iron close for several minutes, then rub the spot clean with a damp cloth.
Sanding can also remove tape residue, but this only applies to wooden or metal surfaces. Using a piece of sandpaper, lightly sand off the residue until it is gone. This method may require a paint touch-up.