My only suggestion is the next time you use red (or any other dark color), first apply a coat of clear polish (varnish) and let it dry. Then apply your dark color. Should make the dark stuff easier to remove later.
Soak your nails in acetone (stronger version of nail polish remover) for about 10 minutes If they have stained yellow though, you will have to wait for it to grow out. Always use a base coat when applying red nail polish to avoid staining.