You may realize a file doesn't fit well in a specific collection so you can remove it.
- Click on the collection you wish to remove the file(s) from.
- Hover over the file(s) you wish to remove and select.
- Click the Remove button that looks like a trash can.
You can also select multiple files within the collection and select the ones you want to remove. Once selected a 'Remove' bar will appear at the top of the page.
Note: The file(s) will be removed from the collection but not deleted from the library.