To edit your email accounts:

Tap on the 3 lined button in the top left of the screen to open the left side panel. Tap on "Email" to show the email screen.
Tap on the cog button beside an email account to edit the account settings.

Tap on the "+" button in the top of the screen to add a new account. You can delete email accounts by swiping left over the account name or tapping on the settings (cog) button beside the account then tap on "Delete Account"