The Mark training for completion functionality will come in handy for you in two cases. Firstly, if the user in question has completed the training, but a long time has passed since the incident and you want to re-train him/her. Secondly, if the user in question has, for example, contributed to a data protection breach and you want to re-train him or her as one of the remedies.
To access the functionality for marking training for redelivery, click on Training -> Training Reports.
Find the user you want to retrain. You will do this most conveniently using the search engine (enter the details of the person you want to re-train in the User field and then click Filter). Click on the Actions button next to the user in question and then - Mark for completion.
And now! The user's training has been marked as Not Started. The user will receive an automatic email notification to this effect. The action you take will not affect the authorisations and certificates already granted to this user (they will not be automatically withdrawn).