Open the Phone app or Contacts app
Tap the contact you want to delete
Tap Edit
Scroll down and tap Delete Contact
Tap Delete Contact again to confirm
To delete multiple contacts, use iCloud on a computer or a third-party contact manager app
To delete all contacts from iPhone, turn off Contacts in iCloud and choose Delete from My iPhone when prompted
To remove synced contacts from an email account, go to Settings
Tap Apps or Mail, then Contacts, then Accounts
Select the account and turn off Contacts
Delete the account if you want to remove all contacts from that account from your iPhone