In the Contacts app, you can add multiple accounts—such as iCloud, Microsoft Exchange, Google, and Yahoo. You can choose a default account, set up LDAP or CardDAV accounts, show or hide accounts, and delete accounts.
Go to Settings > Apps > Contacts.
Tap Default Account, then tap the account you want to make your default.
Go to Settings > Apps > Contacts > Contacts Accounts, tap the account, then tap Sign Out (for an iCloud account) or Delete Account (for other accounts).
If you don’t see Sign Out or Delete Account, your account may be managed by your organization. See an administrator for removal instructions.