There are three main ways of transitioning to gray hair from dyed hair: the cold turkey method (letting the dye grow out or cutting it out), the salon transition (having a stylist blend your dyed hair to match your natural gray), or the dye-strip technique (a combination of various methods).
Buzzing your hair off is a dramatic way to go, but if it suits your personality, go for it! The only disadvantage I can picture is that it might be a shock to “go gray” overnight