It is possible to delete a resource requirement even if resource bookings already exist for this resource requirements. The resource bookings cannot be cancelled afterwards. The following message "msdyn_resourcerequirement With Id = Does Not Exist" appears. The resource booking can only be deactivated.

It would make sense to prevent the deletion of resource requirements for which resource bookings already exist. It would be imaginable to display a notification message or to hide the delete button on the resource requirements in this case.