We know velocity of electron in the $n^{\text {th }}$ orbit is $v_{n}=r_{n} w_{n}$
$w_{n}$ is angular velocity
$w_{n}=\frac{v_{n}}{v_{n}}$
Also, $v_{n} =\frac{z e^{2}}{2 \varepsilon_{0} n m}$
$\therefore w_{n} =\frac{z e^{2}}{2 \varepsilon_{0} n m}$
$\therefore w_{n} \propto \frac{1}{n}$