To deactivate a user within CRM you need to remove the user's CRM permissions before deactivating the user in Evo. This is because it is the removal of CRM permissions rather than the deactivating in Evo that marks the user as Inactive in CRM. You do this within the members screen of Evo. Once you have done this you can deactivate them.
To deactivate a user in Access Evo:
Click Members then use the search bar to search for the employee to be deactivated.
Next to their name, click Show member actions and select Deactivate.