Q: How can I delete other phone histories from my Itune account?

What do you mean by "other phone histories"?  If you mean other phone backups, you go to iTunes Preferences, on the Devices tab you will see the list of backups.  Click on the one(s) you want to delete and click Delete Backup.  (You can hover your mouse over the name of the backup to reveal the phone number and other information if you're having trouble telling which phone the backup belongs to.)

You're welcome.

Thank you so much, this really helped me!