You can remove an iPhone backup from the list of backups in iTunes. You may want to do this, for example, if a backup was created on someone else’s computer.
In iTunes, open iTunes Preferences.
Mac: Choose iTunes > Preferences.
Windows: Choose Edit > Preferences.
Click Devices (iPhone doesn’t need to be connected).
Select the backup you want to remove, then click Delete Backup.
Click Delete, to confirm you wish to remove the selected backup, then click OK.