i accidentally deleted my phone icon from my iPhone 6, how do i get the icon back on my screen?

Deleted? I think your icon has been moved (may be in a folder).

You can't delete phone icon.

See this support article:

Remove built-in Apple apps from the Home screen on your iOS 10 device or Apple Watch - Apple Support

Regards

Giulio

You can't delete the phone icon. You could have moved it to a different page or perhaps turned it off in restrictions.