Hi Marcus,
deleting is actually possible. I assume you are using a object-relationally mapped aggregate? Deleting is considered a state change like any other. The only difference is that this state change sets the "deleted" flag on an aggregate. When the GenericJpaRepository detects this flag (AggregateRoot.isDeleted() returns true), it will delete it from the repository. If you extend one of Axon's abstract AggregateRoot classes, you can use "markDeleted()" to mark an aggregate as deleted.
EventSourcing repositories will not delete anything, they just append the events to the event store. When reading an aggregate back in, they will notice the "isDeleted" flag and throw an exception as if the aggregate doesn't exist.
Hope this helps.
Cheers,
Allard