Desactivation license impossible

Hello everyone, 

I would like to know how to desactivate Trados on my old computer? I have this error message in French (descativation has failed. Impossible to connect to the activation server).

Can someone maybe help me?

Kind regards,

Error message in French stating deactivation failed due to inability to connect to the activation server. It mentions checking the server address and shows error code 403 Forbidden.