Rewrite In simplest radical form x^5/6/x^1/6

I assume you mean:

[x^ (5/6) ]/[x^ (1/6) ]

The rule for dividing similar bases with different exponents is:

(a^b) / (a^c) = a^ (b-c)

In this case we have:

x^ (5/6-1/6)

x^ (4/6)

x^ (2/3)