How to reduce disk space used by Document previews

Issue

We have noticed that half of the backup size corresponds to Document previews from the Document Library.
Is there a way to clean up these files and reduce the backup size?

You can delete the preview and thumbnail files for Documents and Media by following these steps:
1. Go to Control Panel → Configuration → Server Administration
2. On the Resources tab, find to the Clean Up Actions section
3. Execute Reset preview and thumbnail files for documents and media.