Do you want to be an active member in the Guarantee of Origin (GO) market (either producer, supplier or trader)?
Open a CertifHy account with CMO.grexel! This allows you to have an overview about your GOs. It does NOT provide more information such as price levels about CertifHy GOs that are on the market!
Please see here more details of the process.
If you just want to cancel GOs, in many cases the supplier or trader can cancel on your behalf.