code: public void deleteLinkValue(String ownerObjID, FieldDefinition linkDef, String targetObjID) {
          deleteColumn(SpiderService.objectsStoreName(linkDef.getTableDef()),
                       ownerObjID,
                       SpiderService.linkColumnName(linkDef, targetObjID));
      }
docs: Delete a link value column in the object table of the given owning object.
  
  @param ownerObjID    Object ID of object that owns the link field.
  @param linkDef       {@link FieldDefinition} of the link field.
  @param targetObjID   Referenced (target) object ID.