AcMapClassificationManager::Unclassify Method

Unclassifies multiple entities. Unclassifying entities does not trigger internal transactions. Unclassify only entities classified with the currently attached feature-definition file. If you unclassify an entity that was classified with a different feature-definition file, the corresponding tags will not be changed. To remove all existing tags, regardless of which feature-definition file was used, use ClearAllTags().

AcMapObjClass::EErrCode Unclassify(
    AcDbObjectIdArray* paAlreadyUnclassifiedIds, 
    AcDbObjectIdArray& aEntIds
);

Returns AcMapObjClass::EErrCode eOk if all entities are declassified successfully. Returns AcMapObjClass::EErrCode eNoSchemaFileAttached if no feature-definition file is attached to the current drawing. Returns AcMapObjClass::EErrCode eFailed if the process failed for at least one entity.