When you use the Security Agent uninstallation program to remove the Security Agent program from endpoints, the program automatically notifies the server. When the server receives this notification, it removes the Security Agent icon in the agent tree to show that the agent does not exist anymore.
However, if you use other methods to remove the Security Agent, such as reformatting the endpoint hard drive or deleting the Security Agent files manually, Apex One will not be aware of the removal and it will display the Security Agent as inactive. If a user unloads or disables the Security Agent for an extended period of time, the server also displays the Security Agent as inactive.
To have the agent tree display active agents only, configure Apex One to automatically remove inactive agents from the agent tree.