Replying to Tinting your own lens?

I have a a pair of dragon alliance APX's and the tint has half rubbed off, and it just looks super scratched and blotchy. (its not scratched btw)

I was wondering how I would remove the rest of the tint of the lens?

And also, would it be possible to diy tint them another colour? (black or something?)

I have a few other lens's, so I don't mind if I stuff this up