GreenTools for Google Apps (G4G) has been updated to include a function that can both delete a file and empty the trash. The example code shows how this is done:
#g4gdrv_setValue('id':'firstname.lastname@example.org'); #g4gdrv_setValue('file_id':'1Zs4bc3jueqwgw1uLbyo7C5_k_I5pXRfl'); rc = #g4gdrv_deleteFile(errorMsg);
The example above will delete a single file from your Google Drive. If you wish to empty your trash, simply specify the value "
trash" for the File ID (without quotes). If your trash is quite full, the command will return quickly but the actual clearing of the trash will take a little while from the testing and customer experiences we have.
More documentation for G4G, as well as this new function, can be found in the G4G Documentation.