As a former hairdresser, and a person who has been varying shades of auburn for 20yrs.... who has tried on 3 occasions to change the colour.....
I can tell you, it's HARD to get rid of red COMPLETELY. In some cases, impossible.
You can go to the hairdressers, where they'll use a dark brown with ash in it, to dye over it. BUT I have not once seen a case where the red didn't peek through at some point. Either right off the bat... or after a few shampoos.
When mine was done, the brown was so dark, it was near black.. and the red still peeked through, and the brown was so darn dark, I looked horrid. Much too dark for my skin-tone. They ended up adding highlights around my face to soften it...
Guess what happened? Copper came through.
OR you can strip/bleach it, and remove all colour and dye over that.
BUT that tends to be very damaging and drying to the hair.
And that is MOST DEFINATELY NOT something you should attempt on your own.
So, most likely, you'll have to accept that some will peek through. At least a bit, depending on what shade your red is now, and what your natural colour is underneath.
But if you're determined and patient, after several colourings with an ash brown... it should be gone... at least in look.
But be careful if it hasn't all grown out if you add blonde, the red will rear it's head and show copper.
Since I have copper highlights naturally, for me, it was impossible.
I guess it's just as well, I make a better red-head than anything else :lol: