Can I use a return statement in a function returning void?

Yes, you can return from a void function.

Interestingly, you can also return void from a void function. For example:

void foo()
{
  return void();
}

As expected, this is the same as a plain return;. It may seem esoteric, but the reason is for template consistency:

template<class T>
T default_value()
{
  return T();
}

Here, default_value returns a default-constructed object of type T, and because of the ability to return void, it works even when T = void.