Thumbs.db files are created when we select the Thumbnail view for our folders. This file contains the current picture of the directory, and thus acquire some space. to free some more space from your computer just follow these steps to stop these files.

1. Go to Control Panel –> Folder Options.
2. Go to View Tab, and in the first section look for Do not Cache Thumbnails.
3. Tick that option and click OK.

After you do this no more Thumbs.db files will be created. Rest if you want to delete, then you can search for it and then delete.