Removes channels from the given channel pool.
This function allows to remove channels from the pool. This function may block you because the channel to be removed are selected from those which are ready (no message reply waiting). But it may occur all channel from the pool are busy so function will wait until channel gets ready to be removed.
If you try to close more channel than the pool have the function will close only those channel the pool already have. No error will be reported on this case.