If you delete a Nintendo Account with a Nintendo Switch Online membership, you will no longer be able to use the online service with that account.
If you have purchased a family membership, the other members of your family group will also no longer be able to use the service.
Additionally, we are unable to guarantee that cloud save data will be retained after an extended period of time from when your membership is ended. However, you can continue to use the save data that is saved to your system memory.
Please note that we are unable to refund remaining time on the membership if your Nintendo Account is deleted.