Yes. Deleting a Mission or Library item will not delete the content or Users it is related to.

Please note: However, you will lose the analytics, feedback and comms.

To Delete a Mission/Library Item:

1. From the Dashboard, enter Missions/Content Library
2. Select the mission/library item you want to delete
3. Click on Options
4. Choose Delete mission / Delete item at the bottom of the page.

See: How do I delete Content?