There are four co-author biographies at the end of my paper. There are some white spaces among them. I am trying to get rid of them. Is there a way to do it other than -vspace, because I guess it will also cause more problems as I add/remove things from previous pages
You have basically two simple tools.
It always needs tweaks but you don't need to worry as IEEE will ruin your article after receiving the master copy anyway (Confirmed many times by my own experience!).