You can delete a field from a document as long as it has no signer linked to it. To do so, send a request to DELETE /v1/transactions/{transaction_id}/fields/{field_id}:
curl
https://api.universign.com/v1/transactions/tx_DwYGle91EQZA/documents/doc_4dn/fields/fld_r5mL
Note that built-in fields cannot be deleted.
