Removal of field dependencies values via metadata API is not supported by salesforceWhen we deploy controlling and dependent picklists and add dependent values to controlling field values, changes are reflected correctly in target org but when we remove dependent values from controlling field values and deploy through Metadata API, dependencies are not removed from target org.
For example, there are two activity picklists one as the controlling field and the second as the dependent field, so if we add dependencies to the controlling picklist values and deploy them changes are reflected in org.
But sometimes, it can happen that we remove dependencies and after deployment changes are not reflected in the org.
So this functionality is working as per the below documentation: https://developer.salesforce.com/docs/atlas.en-us.api_meta.meta/api_meta/meta_field_types.htm#meta_type_valueset
The above documentation clearly states that "You can add field dependency values via Metadata API but not remove them". It states that "we can add field dependency values via Metadata API but not remove them".