Be Careful Deleting Users in Microsoft Dynamics 365

Deleting users and reassigning licenses in Microsoft Dynamics 365 requires some planning and consideration.  Otherwise, you may experience undesired consequences.  Deleting and deactivating users can be complex and involve multiple administrators.

For Dynamics 365 deployed on premises, you can disable a user, but online you need to remove the license to disable.

Here are some top considerations:

1. Reassign records in CRM. Do you want to reassign record ownership for cases, opportunities, accounts, contacts and other entities?  If so, deleting a user will not do this automatically so you should update with Advanced Find or another approach. 
2. Does the user own workflows?  If so, new system jobs will fail when you disable or delete the user.  This is a good reason to use system accounts that are not subject to change as the owner for these processes. 
3. Deleting users in Dynamics is not the same as deleting them in Office 365.   Some organizations have different administrators for Dynamics and Office 365, so you need to have a process to coordinate these actions.
4. Auditing may require you to keep track of who did what to which records. Do not change a user name to misrepresent the actors in past transactions. 

You can run into trouble when users own personal views that they've shared with others.  Another wrinkle can occur if you decide to delete a user and then create a new user later with the same name.  This is more likely for common names and in large organizations, but can also happen with admin and test accounts.