If a user is leaving your organization, you can simply click the section Users and hover the mouse over the user that is leaving. When you hover the mouse of a user in the table a more button will be displayed, this is the button with three horizontal dots. Click the more button and then select the option Remove user.
If the employee hasn’t quit the organization but won’t be using 2c8 Apps for the time being, you can instead remove the license from the user but keep the employee as a user in the portal in case the employee might work with 2c8 Apps again. To remove a license from a user, click the section Applications. Select the application the user has a license for, hover over the user you want to remove the license from. On hover a more button will be displayed, this is a icon with three horizontal dots. Click the more button and select the option Remove from application. You will then be presented two different options, if you want to assign the license to another user or if you want to delete the license.