How to delete your iPod or iPhone backup from your computer. Doing so might save you a bit of hard drive space. It’s also good to keep things clean if you no longer sync the device with your computer any longer.
1. Open iTunes.
2. Mac users select iTunes > Preferences. Windows users select Edit > Preferences.
3. Select the Devices tab.
4. Select an iPod or iPhone on the list and click Delete Backup.