How to remove CSP partner relationship in the Office 365 Admin Portal?

I need to remove a CSP Partnerrelationship in the Admin Portal to enable direct support tickets to Microsoft. Direct support tickets are only possible if O365 Licenses were bought from Microsoft directly.

Here is my story. Perhaps someone can help?

1. Created a new tenant, added "X" as CSP partner, added E3 trial from the CSP's cloud portal
2. Setup tenant with the E3 trial licenses, then realized that there is no Microsoft support (I had an issue with migration) and CSP "X" does not provide technical support.
   1. Result: cannot open support tickets.
3. Added advisory partner "Y" as I have access to it's Office 365 partner portal. That way I could open a support ticket. Still I cannot open a new support ticket from inside the tenant, even when logged in with a global admin account.
4. Then I ordered, installed and deployed 16 Office 365 Business Essentials licenses (not trial), purchased  directly from Microsoft from within the tenant. None of the original trial E3 licenses is used anymore. I cannot remove those E3 licenses completely.
5. Direct support tickets from within tenant are still not possible.
6. Then I tried to remove the CSP partner "X" relationship. This seems not possible, no remove link available. Yet, I could remove the added advisory partner "Y" (remove link does appear when that partner is selected), but then I would loose the possibility to open tickets over it's partner portal.

I have some hope that support tickets from inside the tenant become possible again as soon as the CSP partner "X" is removed.

How can I do that?

Thanks

Daniel