Line Managers, Administrators and Content Creators can manually override a Certificate expiry for specific Users. Navigate to the Users tab of the activity, tick the checkbox next to the User's name from the list, then from the Actions drop down choose to either extend or reduce the expiry date.
You can override the certificate expiry date for multiple users at the same time. If you select more than one User you will be presented with the following popup.
You can set Email Reminders based on Certificate Expiry. See the Set up Email Reminders guide for more information.