The supported methods to uninstall the Syslog-ng Windows Agent are using the uninstall.exe locally or by using the domain install/uninstall.
If the Syslog-ng agents were installed from a Domain Controller using the .msi via GPO then they can be removed from there as well using the Group Policy Management Editor.
Please see the following for the .msi domain uninstall method:
If the Syslog-ng Windows Agents were stand alone installations then it is also also possible to utilize Group Policy by pushing a start-up script that uses the uninstall.exe with the silent uninstall switch.
Please see "Procedure 2.5. Uninstalling Syslog-ng Agent in silent mode" in the admin guide:
For example: "C:\Program Files\syslog-ng Agent\Uninstall.exe" /S
Please note that scripting is outside the scope of One Identity Support.
The One Identity PSO teams can assist with scripting. For more information on this please contact your One Identity account representative who will be able to provide options.