RE: Unsubscribe from event
Hi Filippa,
I think the meaning of “Unsubscribe from event” is cancelling the registration.
You can find a statement that “To cancel an event registration from within Marketing, simply deactivate the record.” in the following link.
Initial and ongoing event planning (Dynamics 365 Marketing) | Microsoft Docs
If you’d like to cancel the registrations with customer journey, it must be processed with a workflow. However, In a customer journey, only the workflows targeting at Contact entity can be inserted into for the audience is always a collection of contacts. The event registrations cannot be set as inactive in these workflows. As the one-to-many relationship between the Contact and Event Registration entity, which means that one contact can be registered several times even for the same event, we cannot uniquely identify a registration based on a certain contact.
So you need to deactivate the registrations manually if you’d like to cancel event registration without portal.
If this helped you, I'd appreciate it if you'd mark this as a Verified Answer, which may in turn help others as well.
Best Regards,
Nya