How to uninstall USB to VGA Adapter's drivers?
Usually drivers come with an uninstaller. Redownload the installation package/dmg of the driver if necessary and use the uninstaller included there.



In the specific case, the driver can be redownloaded from the web site linked in the question.



It contains both an installer and an uninstaller. From looking at it, the following files get removed

/Library/Audio/Plug-Ins/HAL/MCTT6Audio.driver
/Library/Extensions/MCTTrigger2.kext
/Library/Extensions/MCTTrigger6USB.kext
/Library/Extensions/MCTTriggerGraphics.plugin
/Library/Extensions/Trigger5Core.kext
/Library/LaunchAgents/com.mct.USBVGASync.plist
/Library/LaunchDaemons/tw.com.mct.TriggerDriver.plist
/System/Library/Extensions/MCTTrigger2.kext
/System/Library/Extensions/MCTTrigger6USB.kext
/System/Library/Extensions/MCTTriggerGraphics.plugin
/System/Library/Extensions/Trigger5Core.kext
/System/Library/Services/USBVGASync
/usr/local/libexec/MCTTriggerDriver
/usr/local/sbin/USBVGASync


After removing the files a restart is required.