T-SBADV-010-006
If you want to remove a folder from your libraries, you must first understand the difference between a library and a sub-folder in a library. A library is a folder added at the root of your libraries list, and it is indicated by a  icon. A sub-folder is inside one of the libraries in the libraries list, and it is indicated by a 
 icon.
You can close a library , which will remove it from the Library view, but not from your hard drive. However, you cannot close a sub-folder 
. All the sub-folders in a library are always available in the Library view. However, you can delete sub-folder 
. This however will delete it from your hard drive permanently. 
Hence, in summary:
- You can close a library , which will remove it from the Library view but not from your hard drive, but you cannot outright delete a library from Storyboard Pro. 
- You can delete a library sub-folder , which will permanently remove it from your hard drive, but you cannot simply close a library sub-folder. 
Hence, if you find that some sub-folders are incumbering your library, but you don't want to lose their content, it would be best to open this library in a file browser, and move those folders somewhere else where you can retrieve them later.
 How to close a library
How to close a library
                                                            - In the left pane of the Library view, select the library folder that you want to remove. 
- Right-click on the library and select Close.
 How to delete a library sub-folder
How to delete a library sub-folder
                                                            - In the left pane of the Library view, browse to and select the library sub-folder that you want to delete. 
- Do one of the following:- Right-click the selected library and select Delete Folder.
- Press Del.
 
A confirmation prompt will appear.
If you are sure you want to permanently delete all the content of the selected folder from your hard drive, click Yes. Otherwise, click No.