There are a few ways to make Altezza/Euro taillights.  You can use nail polish remover, but you can melt your lights.  Just fill a cup with some nail polish remover and leave the lights in there until they appear clear.  Or a better way is taking some rubbing alcohol and a razor blade and scrape the red off (NOTE: This may take some time).  Then to create brake lights and signals take a red permanent marker and put a dot(s) on the light.  For reverse lights take some white paint and make a dot(s) on the light.