Hair dye build up, and how to fix it?

[Hotpinkkk]

My hair has a lot of hair dye build up.

The roots are lighter (noticeable, but not extremely), and the rest is darker. Even though I have been using shades like Light Ash Brown, and plain old Medium brown, the ends have become quite dark due to build up. 

I don't feel I look good with such dark hair, but I don't really know how to fix this myself.

I'm afraid if I use a hi-lift color OR bleach, my roots will turn really light, and the rest will still be much darker. Also, my roots are very ashy, and the rest of my hair has a red/warm/orange tinge.  (I put this in bold because this is my biggest concern)

Should I only lift/bleach the ends, and avoid my roots? Or would it be okay to use a hi-lift color on my whole head? 

Though edited, you can see about 1/2" of roots here, and dark build up on the rest.

 

[zadidoll]

There are products on the market to strip the dye color. If you bleach your hair it won't completely remove the dye. My middle daughter loved to dye her hair black (natural color dark brown) then decided she wanted to go purple. I had completely forgotten we had dyed her hair black at one point and so when we bleached her hair it turned a dark brassy color while her virgin hair went lighter. It's been a nightmare getting her hair even and when the purple was applied it lasted one week. Best thing to do is go to a beauty school - if possible - and have them do it.