You might have backed up data of your iPhone or other devices in your computer or other people's. If you don't want them, how can you delete them? These useless backup files clog up memory. You can delete them to prevent your privacy following the below steps.
1. Connect your iPhone or other iDevices to your computer and turn on "iTunes" in your computer. In the Menu bar, go to iTunes > Preferences. (If you're on a Windows PC, go to Edit > Preferences).
2. Click "Devices" in the "Preferences".
3. All the backup file of your device in iTunes will be listed in the window. Select the backup you want to delete.
4. Click on the Delete Backup button. You will see this popup window asking you to confirm to delete the backup. Click "Delete" to confirm.
Notice: The backup file will be permanently deleted if the above operation is done.