If you are planning to re-install Windows 7, just boot off of hte Windows 7 media and start a clean new installation. You can format the drive during the install process.
You may want to post future questions about Windows 7 in a Windows 7 related forum, instead of "Server Manager".
http://social.technet.microsoft.com/Forums/en-US/category/w7itpro
Visit:
anITKB.com, an IT Knowledge Base.
