There should be a minimized icon in the system tray. Right mouse click on it and choose 'close window' to end the uninstallation.
Launch task manager and end the process setup.exe, if it is still running.
Verify the following components have been removed from the APM web and APM application servers:
Note: The APM installer checks for this entry, and if present, launches the 'Repair/Uninstall' window.
If this key is not present, then reinstallation is allowed.
Restart the server(s), and APM is ready for reinstallation.