The g2awinlogon.dll file is a component of GoToAssist from Citrix Online. GoToAssist is a program that allows a company to remotely access a PC for diagnostic purposes. When you give a technician access with GoToAssist, they can work on your machine as if they were sitting in front of it, from a support office miles away. If you have allowed a company remote access to your computer for diagnostic purposes, this file might be needed on your computer.
If you have deleted this program from your computer without uninstalling it, you might get a registry error that lists this file. To fix the problem, you would need to remove the registry entry for the file. However, editing the registry is a complicated task that could have dire results if you make a mistake. Rather than risk breaking your computer, you should run ZookaWare PC Cleaner to clean your registry for you and fix any registry errors you have.