To ensure that your library items are not accessible via the Library Marketplace, just follow the steps below!
Disabling sharing can be done individually, or en-masse, just like applying labels. If you want to make your entire library inaccessible to the marketplace, you can!
1. Go to your Library
2. Click Edit
3. Select Library items
Clicking Edit will allow you to check items in your library. Just check the boxes of items you want to share or remove the ability to share.
4. Click Share
5. Select your options
Once you click on Share, a small menu will appear allowing you to select to share, whether to include your items in Search, whether to allow others to copy, etc.
6. Finish
Click on Apply, and then Done, and you're good to go!