What’s happening?
Customers are unable to hide the modern "Share" button on the command bar in Dynamics 365 apps.
Reason:
The modern 'Share" button cannot currently be disabled through a UI setting of customization.
Resolution:
For the modern "Share" button in Dynamics 365 apps, Microsoft can disable this through a back-end configuration. Customers needing this functionality disabled must request Microsoft Support to perform this change on their specific environments. This action can only be performed by Microsoft Support and is not available through standard customization tools such as Ribbon Workbench.