As Users and/or staff move on, you will more than likely finding the need to Mark a User Account as Inactive or the need to Delete a user account.
Please note: you will need to double check to see if the user has any Scheduled Reports associated with their User Account and either remove them or adjust who the Scheduled Reports are associated with by going to Reports > Scheduled Reports.
To Mark a User Account as Inactive
You need to go to Settings > Users & Security > Users & Security.
Select the User you need to Mark as Inactive.
Click the Cog Icon.
Click Mark User as Inactive.
To Delete a User
You need to go to Settings > Users & Security > Users & Security.
Select the User you need to delete.
Click the Cog Icon.
Click Delete User.