When you delete a file in Google Drive, the file is sent to the trash or bin, not effectively deleted. The bin eats disk quota so, if you doesn't empty it quite often, you can get easily out of space.
EmtyTrash GDrive is a simple Windows App that can be used to empty trash on demand or in a daily basis.
This app does not store any personal information, but relies on Google Drive and Google Auth standard libraries that use its own mechanisms to get access to your account information. As a part of this process, when the application is opened for the first time, your default browser will be opened to select which of your Google Accounts will be used.
Depending on the size of files contained in the bin, it can take some time (1-2 minutes) to empty. Please be patient.