Error Message No. 00 058

We have configured values for Additional Customer Data (KNVV-KVGR1). A contract was created with value 536 in that field. We have since deleted that value from the configuration. When we attempt to make any change to the contract error msg 058 - Entry does not exist is received. However, system will not let you proceed to the field in the document to change it to a valid entry. Can this message status be changed to a warning? Or do we have to replace the 536 value until all documents are changed?

Thank you, Julie