If you are receiving an error "Cannot Create Account - An identical Subscribed Calendar account already exists.", here are the steps you need to unsubscribe from the calendar that is currently setup.
- Unsubscribe on iPhone (iOS 10)
Tap Settings
Tap Calendar (in earlier iOS versions tap Mail, Contacts, Calendars)
Tap Accounts
Tap Subscribed Calendars
Tap the "TeamSideline Calendar" to remove it
Tap Delete Account
Tap Delete Account to confirm
- Unsubscribe on iPhone (iOS 11&12)
Tap Settings
Tap Passwords & Accounts
Tap Subscribed Calendars
Tap the "TeamSideline Calendar" to remove it
Tap Delete Account
Tap Delete Account to confirm
- Unsubscribe on Google Calendar
Open Google Calendar
In the top right, click the Settings icon then click Settings
Click the Calendars tab
Click the Unsubscribe link to the right of the "TeamSideline Calendar" calendar you wish to remove.
- Unsubscribe on iPhone 7 (iOS 10)
Go to Settings>Calendar>Accounts
Tap Subscribed Calendars
Tap TeamSideline and then tap delete.