Delete empty space in multitrack

I am trying to delete "empty spcace" in a multitrak podcast template. I created a podcast template with my intro and outro with several minutes in the middle to add interview audio to. When the audio does not fill the gap or there it not enough gap, how do I delete empty space or add to it? If you view the image I have attached you can see the gap in the middle of the track that I am currently trying to remove. Thanks.