Answer
$h=\frac{S-2\pi r^{2}}{2\pi r}$
Work Step by Step
We are given that $S=2\pi r^{2}+2\pi rh$. We can first subtract $2\pi r^{2}$ from both sides.
$S-2\pi r^{2}=2\pi rh$
Divide both sides by $2\pi r$.
$h=\frac{S-2\pi r^{2}}{2\pi r}$