I can't remove space from computer, keeps adding more everytime i delete an application

I recently attempted to clean out my computer to allow myself more room. Upon deleting a 20gb game and restart my computer i had found that my minuscule 24gb of free space went down to 20gb of free space despite the application, along with the actual files themselves, no longer on the computer. I also cannot now redownload the application because I don't have enough room to do so