How to remove remove duplicate contact persons

How to remove remove duplicate contact persons

Is there a way to de-duplicate contact persons within books?

Or any way to bulk manage the contact persons who have invalid data via API?

Using the CRM / Books integration and running into lots of issues with duplicate contacts and bad contact info. I've about 3,000 sync issues which I'm hoping Zoho don't tell me I've have to go through one by one!