Dark hair color removal?

I started going gray in highschool (16) and started dying my hair to hide it. But in the last 15 years my gray to brown ration is about 60/40. I'm tired of dying it none stop and have decided to just let it go. But I'm wondering if theres a way to get rid of any of some of the dye? My color now is a deep brown (NOT BLACK) I would like to lighten a few shades, I'm around a 3 shade now and would like to be around a 5-6 to help ease in the gray. Ive used Selsun blue to help rinse out some dye (yes it helped a little). I'm avoiding bleach and stripping hair. Any advice??