There are effectively two ways to delete and attribute. The first is to explicitly delete an attribute value instance by the attribute's unique URI for the value you want to delete. You can see some details here:
https://docs.reltio.com/attributeapi/deleteattribute.html
If you have challenges with this one, post a sample record payload from a GET entity, and we can try to give you a more tangible example.
The second option is the bulk attribute actions. Performance will be somewhat slower, but it will allow you to delete a specific value without knowing the URI. Note that you need to be careful with this second approach as it can impact multiple records if your filter criteria is too broad.
Use the operation DeleteAttribute as documented here:
https://docs.reltio.com/entitiesapi/bulkattrupdate.html
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Dan Gage
Principal Solution Consultant
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