As such, you cannot remove the projects that are listed in the Visual Studio recent projects list on the Start page. One option is the find the projects which you want to remove in the location specified by the shortcuts, then either delete them or rename them and come back to VS and click the project name, you will get a message box asking you whether to remove the entry from the list.
Another option is to edit the registry entry (Warning! All registry edits should be done at your own risk).
I found a nice blog post explaing all of this, I am just pasting what I may need in future here:
Visual Studio Recent Projects
Visual Studio .Net keeps it's list of projects in the registry. Depending on which version depends on which location the list is stored.
· Visual Studio 2002 - 7.0
· Visual Studio 2003 - 7.1
· Visual Studio 2005 - 8.0
· Visual Studio 2008 - 9.0
[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\7.0\ProjectMRUList]
[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\7.1\ProjectMRUList]
[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\8.0\ProjectMRUList]
[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\9.0\ProjectMRUList]