Vues :

How can the signature/certificate for Connect to SAP be deactivated?

You need to deactivate the signature on DocuWare and SAP side.

On DocuWare side use DocuWare Administration, go to Server > Connections.
Disable the flag 'Enable secure communication'  and restart the SAP HTTP Service.

On SAP open the transaction 'OAC0'. Enable the flag 'No signature'.