You can run the Microsoft Entra ID user status batch job to disable users in D365 FO if these users no longer exist in the Microsoft Entra ID.

Standard procedure

1.	Go to Security and compliance > Periodic tasks > Apply Microsoft Entra ID user status
2.	Expand the Run in the background section.
3.	Select Yes in the Batch processing field.
4.	You are advised to run this batch job in a recurring pattern. So, you always have up-to-date license usage counts. And so, you can reduce license costs.
	Click Recurrence.
5.	Define the recurring pattern as desired.
	Click OK.
6.	Click OK.