You could try a coke bath, or hydrogen peroxide, but mint is a very pungent flavour, and complete removal will be very difficult. I'd advise keeping that atty for minty flavours, and break out a new one if the flavour you want next is incompatible with mint. You can waste a lot of time, and possibly add wear to your atty by trying to remove every last menthol molecule with aggressive chemicals.
Alternatively, just vape a fruity flavour through it until the mint diminishes of its own accord (most fruit flavours are quite nice with a hint of mint.)
Yeah! coke bath did the trick, no more noticeable mint residue.
I had also tried vaping the flavor away but I did not have much success there. Thanks!