If you'd like to delete files from your Virtual Classroom account library, you can do it from your library or a classroom:
From your LearnCube dashboard:
Click on "Content Library" (top-right).
Find the file you'd like to delete and click on "Edit".
Click on "Delete" (top right).
If you're in a classroom and would like to delete a file:
Click on the file icon in the menu options on the bottom-right of the screen.
Find the file you'd like to delete and click on the trash icon.