The content manager is able to change the email address and phone number that is shown for the Customer Support section of the footer.  If you want to change the copy displayed, that will require a developer to edit the page template.

Editing Customer Support Information

Navigate to: Stores & Reps > Stores> choose your store >  General

The Customer Service Email and the Customer Service Phone Number from here are used in the Customer Support section of the footer.

Publish the Store to see the changes on your storefront.