When you add your Google account to your iPhone or iPad in the Settings app, add your Gmail account to the Mail app. If you prefer to use third-party email clients, you can delete email accounts from the Mail app on your iPhone or iPad.
The Settings app allows you to sign out of any email account (including Gmail, Outlook and iCloud)) while still using the account to sync notes, contacts, and so on.
To do this, open the "Settings" app on your iPhone or iPad and go to the "Passwords and Accounts" section. [1
Here you will see all the accounts you are logged in to. Tap an account to see the fine details.
Then tap the switch next to the "Mail" option to disable email synchronization. You will notice that the specific email inbox disappears from the Mail app.
You can go back to the "Passwords and Accounts" section and follow the same process for deleting email accounts from other services.
The process of disconnecting email accounts from the Mail app works for all third-party accounts. If you want to delete the iCloud email account, the steps are slightly different.
Open the "Settings" app and tap your Apple profile at the top of the menu.
Tap the "iCloud" option here.
Now scroll down and tap the switch next to the "Mail" option. 
Your iCloud email is now disabled and will no longer appear in the Apple Mail app.
To confirm, you can open the "Mail" app again. Instead of seeing your usual email inbox, you'll see a welcome screen asking you to sign in to an account.
If you don't like using Mail app, we recommend the Gmail app. And if you want something with extra features and a better fit and finish, try the Spark app.
Will you stick with the Mail app for one of your accounts? Configure the email settings for a better experience.
RELATED: How to Configure Email Settings for iPhone and iPad