Hello, Sebastien Norroy.
Welcome to Microsoft’s Community.
Based on your inquiry, we understand that you need to change your work account (ADD) to your personal account (MSA) because you will no longer have access. However, you are unable to access your profile with your work account. We are happy to assist you with this.
We’re providing this information because of recent updates to our internal policies.
We want to inform you that to change your Microsoft account, you need to have access to it. The process is done within the account, so if you can't log in, you won't be able to switch to your personal account
That is why it is important that users have access to their own Microsoft accounts and that there are no harms with losses and thus be able to prevent third parties from accessing their accounts.
In this situation, we advise candidates to use personal accounts rather than work accounts to avoid any future disconnection issues with work or study accounts.
We understand that it can be frustrating given the time you have invested, but please be aware that these measures are due to internal security policies.
Alternatively, we encourage you to create an account with a personal email to obtain future certifications.
For additional information, you can click on the following link: Microsoft Learn frequently asked questions (FAQs) | Microsoft. If you want to find information on different topics, you can navigate to the section at the beginning of the link and choose the topic you’re interested in.

We eagerly await your input. Should we not receive a response from you within one (1) business day, we will proceed to close both this case.
Best Regards,