With the button you can revoke a listed certificate. To do this, you must select a reason and enter the password of the private key of the certificate's parent CA.
Certificates cannot be revoked if
- the certificate was revoked already,
- the certificate does not have a CA (first-level CA) or
- the CA of the certificate does not have a private key.
Use the buttons in the lower right-hand corner of the editing window to revoke the selected certificate or to cancel the dialog (Cancel).