How to delete old iPhone back ups and library data?

I'm trying to free up data on my iPhone/laptop and I know restoring your phone and reuploading things frees up space (at least it has for me) but I don't have a lot of laptop space. I've tried doing it before but it says I don't have enough space and the current back up that I'd attempt takes up space. I was wondering how can I delete old back ups for my phone/library.

Open iTunes
Edit > Preferences
Click the Devices tab from the top row
If there's anything in the Device backups: box, delete it.

That will clear some space on the laptop

On the iPhone, things you can delete are
- Apps you don't use
- Photos
- Videos
- Music
- Voice memos