how to know where my iPhone backup is in my Mac ?

One can Not open it - it is a Backup of the iPhone and macOS High Sierra only stores it because one choose to Backup to the computer.The Backup of the iPhone is only useful to Restore the iPhone if required. Should the Backup of the iPhone is taking up needed space on the computer, one can remove the Backup

Go About this Mac >> Look for tab Storage >> Manage >> on left are categories including IOS File