Can I switch off opt-in and opt-out consent messages, e.g. those used for marketing?

Can I switch off opt-in and opt-out consent messages, e.g. those used for marketing?

At Volcanic, we have set up our portal exactly as stipulated by the articles of the GDPR, which recommends the self-service model as best practice. Switching off opt-in consent, to receive marketing material for example, is not possible as specific, pro-active, transparent consent is a core requirement of the GDPR.