How do I remove gmail contacts from the contact list on my Iphone 6

Go into settings, accounts and passwords. Look to see which email account shows contact. Select it and on the next screen select don’t allow on contacts. It will remove the email addresses in your phone contacts. I just finally figured it out on my own.

If your contacts are not syncing with any external service, meaning that the contacts only exist on the iPhone, you may be able to take advantage of a particular iOS backup limitation. Your backup does not contain all of your contacts*, so if you restore your iPhone and reload your backup, that may skim off the contacts that were loaded, but that of course may contacts that you want to leave on the iPhone. You should use some sort of external contact manager eventually.

*Apple is not entirely clear about local contacts and backups, and there is some disagreement among users here. The article below states:

Your contacts are part of the backup to preserve recent calls and favorites lists. To avoid any potential contact data loss, back up your contacts to a supported personal information manager (PIM) or another cloud-based service (such as Gmail or Microsoft Exchange).

Contacts sync and backup on iPhone

Sounds like the person at the store actually imported them into Contacts. Unfortunately, that means you will likely need to delete them manually. If you are not syncing with iCloud - and it sounds like you are not - this will mean deleting them on at a time.

Assuming it is just syncing with Gmail: Settings app > Mail,Contacts,Calendars > [your Gmail account ] > [turn OFF Contacts]

Are you able to send and receive email? And if so, are you using the native Mail app, or something else?

Sorry.