How do i delete country from my mailing label format
There are two ways to do this.


If you are based in the United States, go to Administer > Localization > Address Settings.  Set Hide Country in Mailing Labels when same as domain country to Yes.  You can double-check that CiviCRM thinks you're US-based by going to Administer menu > Communications > Organization Address and Contact Info and checking the Country field under Default Organization Address.
If you are NOT based in the United States, go to Administer > Localization > Address Settings.  Remove {contact.country} from the bottom of the Mailing Label field.  Note that this removes country for ALL mailings.
If you need something more fine-grained (e.g. you're not US-based, but need to remove country from mailings sent to the US), install my extension com.megaphonetech.addressl10n.  This will let you do per-country mailing label formats.