How to close the preview in the file browser?

I mainly use WaveLab for batch editing.
When I drag files from the file browser into batch processing, the small preview windows always opens the first file for preview. With the stupid mistake that this file is NOT rendered - because it is open (Medium is write-protected).
It is not possible to push a single file into the batch process - because this will open the file in the preview. So the file is marked red (Medium is write-protected).

I can’t find a way to remove this preview window. So at the moment I’m still using version 9.5. Please help.

Simply drag this bar at the bottom:

Thank you - unfortunately this will not help.
Even if you drag the window to the bottom, the preview process will open the file. So the file is still locked. Even if you don’t see the waveform.
The preview process accesses the file even when the window is closed.
So this file cannot be rendered.

Just tested with WaveLab 10.0.50 and it works. But you need to hide the preview before clicking on the file.

Thank you.
The file may only be marked after the window has been closed.
Thank you - works now.