# Update or Remove Classes and Classifiers

To update or remove a class use the following actions:

- To add additional training images to a class, use the action `AddClassImages`. After adding images to a class you must retrain the classifier using the action `BuildClassifier`. To confirm that training was successful, use the action `ListClassifiers` (see List Classifiers and Classes).
- To remove training images from a class, use the action `RemoveClassImages`. After removing images from a class you must retrain the classifier using the action `BuildClassifier`. To confirm that training was successful, use the action `ListClassifiers` (see List Classifiers and Classes).
- To change the label of an image that you added to a class, use the action `RelabelClassImage`.
- To move an image from one class to another, for example if you add an image to the wrong class, use the action `MoveClassImage`.
- To add, remove, or update custom metadata for a class, use the actions `AddClassMetadata`, `RemoveClassMetadata`, and `UpdateClassMetadata`.
- To rename a class, use the action `RenameClass`.
- To remove a class from a classifier and discard all associated images and metadata, use the action `RemoveClass`.

To update or remove a classifier, use the following actions:

- To modify the training options for a classifier, use the actions `SetClassifierTrainingOption` and `UnsetClassifierTrainingOption`.
- To rename a classifier, use the action `RenameClassifier`.
- To delete a classifier and all of the information that it contains, use the action `RemoveClassifier`.

For more information about the actions that you can use to train Media Server, refer to the Media Server Reference.

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