Note that the user is not really deleted. You are simply removing the user from the initiative or organization they are a part of. You can add the user back if it is required in the future. The user is only truly deleted if he/she or someone who has their credentials actually logs into to the system and delete their account.
Important: If a user wants to delete their account completely then please make sure any Organizations and Initiatives they own are transferred to someone else before the account is deleted.