Overview

You may face the issue where you've tried uninstalling the EndPointSecurity Agent from one of your computers but every time it comes back in the console with a running GFI service. 

A detailed example:

After uninstalling the GFI EndPointSecurity agent in the console, Deployment Status was written:
Uninstallation: The GFI EndPointSecurity protection agent was not detected on this computer.
Uninstallation: The uninstallation was completed.

After that, checking Services on that computer, you  can find the following:
-GFI EndPointSecurty Agent Installer Service -Status: running
-GFI EndPointSecurty Agent Service -no status (blank)

The next day you receive in GFI, the console message: Computer xxxxxxx was detected with agent already installed.
After checking services on that computer again:
-GFI EndPointSecurty Agent Service is in status: Running
-other service (GFI EndPointSecurty Agent Installer Service) was not there anymore.

In the process, you used the suggested steps in Removing Computers from the GFI EndPointSecurity Console.

Information

Please exclude machines on the network where you don’t want to deploy EndPointSecurity Agent by excluding them from auto-discovery: Excluding Computers from Auto-Discovery. The reason is, if the computer is found by the auto-discovery after Manual uninstallation, the Agent will be installed again.

Then to solve the main issue you'll have to remove the agent manually. Please refer to the EndPointSecurity | Removing agent manually article to do so.