Deleting a contact will remove the contact from the group's records and anonymise all historical transactions related to this contact. Deleting a contact is permanent and cannot be reversed.
Archiving the contact will remove them from the group's contacts list. You can restore an archived record in the future if needed.
More information can be found via the Clubspark Support pages: https://sportlabs.zendesk.com/hc/en-us/articles/16155474123677-Deleting-Restoring-a-Contact