Applicant: The natural person or Legal Entity that applies for (or seeks renewal of) a
Certificate. Once the Certificate issues, the Applicant is referred to as the Subscriber. For Certificates issued to devices, the Applicant is the entity that controls or operates the device named in the Certificate, even if the device is sending the actual certificate request.
Subscriber: A natural person or Legal Entity to whom a Certificate is issued and who is
legally bound by a Subscriber Agreement or Terms of Use.
Subscriber Agreement: An agreement between the CA and the Applicant/Subscriber that
specifies the rights and responsibilities of the parties.
Sure, Cloudflare certainly can request in writing from the CA to revoke the certificate - but in this case the problem was that they did not, right? Your best bet would be to email DigiCert directly under BR 4.9.2 (Who can requst revocation) at revoke@digicert.com [0], citing termination of the contract between you as the Domain Name Registrant and the Subscriber (i.e. 4.9.1.1 pt 4 as mentioned in the parent comment).
