Hi and thanks for reaching out! I'm an Independent Advisor and a Microsoft user like you. Please allow me to assist with your issue.
You could add a registry entry to block OneDrive from Office. To do so you should be comfortable modifying the registry and always make backup before doing so.
Add or Modify the DWORD value "OnlineStorage" under HKCU\Software\Policies\Microsoft\Office\16.0\Common\Internet.
Available values are:
0 - Policy is off (all locations are shown)
1 - Only OneDrive Personal locations are hidden
2 - All SharePoint Online locations are hidden
3 - All Microsoft Online Locations are hidden
https://docs.microsoft.com/en-us/office365/trou...
Please let me know if I can help you further!