Obviously the nail polish needs to be taken off the nails especially when it starts to chip or when a different colour is to be used. Nail varnish removers contain solvents which dissolve the nail polish, so that it can easily be wiped off with cotton wool or a clean tissue. The important thing is to choose products that are free from (or low in) acetone as they strip the nails, cuticles and surrounding skin of moisture. Choose varieties that contain moisturising conditioners.