Cases in Wildlife Rehabilitation MD can not be deleted.
If you have a case that you would like to delete, the better option is to write a new case over the mistaken case. For example: replace the values in the fields of the mistaken case with values that match your new case. Be sure to change the species if needed.
If the mistaken case is part of a group of related records (i.e. multiple animals brought in by one rescuer) you must detach the rescuer information from the mistaken case before changing it. If you do not, all records brought in by that rescuer will be mistakenly updated.