VS2010: how to remove/hide the "External Dependencies" folder in Solution Explorer
Don't know if you figured this out yourself but looking at this page you can disable it in the Options dialog (from the Tools menu).
On the right side panel expand the Text Editor section, then expand C/C++ and then click on Advanced. Set the Disable External Dependencies Folder to True and restart Visual Studio.
As mentioned by Michael in the comments, apparently you don't need to restart Visual Studio but can just close and re-open the solution to see the effects.