Open the account profile rather than creating another identity
Radio-Canada’s current account-management help directs signing into mon-compte.radio-canada.ca. The default Profil tab allows changes including email, password, name and other personal details. Enter the intended change and use Enregistrer. This is an edit to the existing account; beginning a fresh registration is a different operation and is not the documented first step for an ordinary email update.
Read the one-address rule
The help says an email can be associated with only one account. If the desired address already belongs to another profile, that relationship must be released before it can be reused. Radio-Canada lists changing the email on that existing account or deleting the old account if it is no longer useful. First establish which account holds the address rather than repeatedly resubmitting the same occupied value.
Recover an existing account when the address is recognised
Radio-Canada’s already-associated-address help says one account is used across its platforms and directs signing into the existing identity. If its password was forgotten, use the reset route it supplies. A recognised email can therefore be a reason to recover that account, rather than assuming the service needs a second registration with the same address.
Choose the intended account before saving
On a shared browser, check the current account profile and the address you are editing. If both identities still serve a purpose, use an appropriate distinct address rather than deleting one solely to make a form accept another value. When an unused account has an active subscription, Radio-Canada’s separate deletion rules also need attention before that account can be removed.