Go to Planning & registration - Planning - Training planner
Look up the relevant training and click Edit (pencil icon)
Click the tools icon for the relevant session
Under 'Status', choose 'Cancelled'
You choose whether or not to send a notification by selecting or clearing this option.
You enter a reason, in which you state what you want the participants to do (for example register again themselves).
Finally you choose to move users to another session, to move them to the waiting room, or to remove everyone from the training.
The chosen action is carried out. Notifications are only sent if you selected the notification option.
The session is then archived. In the overview screen Sessions, click Show archived to view these sessions again.