Remove Classification Enum Option

Hello,

I would like to remove an option from a java classification.
I use the following code:

List<MetadataTemplate.FieldOperation> updates = new ArrayList<>();
delete.setOp(Operation.removeEnumOption);
delete.setFieldKey(“Box__Security__Classification__Key”);
delete.setEnumOptionKey(option.getKey());
updates.add(delete);
return MetadataTemplate.updateMetadataTemplate(boxAPI.getAPI(), boxAPI.getScope(),Metadata.CLASSIFICATION_TEMPLATE_KEY, updates);

but I get the following error:

The API returned an error code [403 | q5q8oghr0krwv557.0be56fb8d3a04661fa87b95f7aa219311] forbidden - Template operation can’t be performed due to existing policies on the template.

thank you in advance for your help