Answer
Angular velocity remains the same at that instant in both a) and b).
Work Step by Step
We know that when there is no angular acceleration, angular velocity $\omega$ stays the same, so if $\omega$ is zero, it will continue to be zero, and if $\omega=a$, it will continue to have that same value.
In both cases, either additional torques are added or all torques are removed, the result is $\sum\tau=0$. According to Newton's 2nd law of rotational motion, $$\sum\tau=I\alpha$$
that means $\alpha=0$. Therefore, angular velocity remains the same at that instant in both a) and b).
