The SharePoint farm administrator (or site collection administrator) can't delete or make changes to a specific site. When trying to delete the site, the error message is that the user doesn't have permissions. When trying to modify settings, the error message is: You need to be a site collection
administrator to set this property.
The site is locked.
Go into Central Admin unlock the site. (In SharePoint 2007: Application Management, Site Collection Quotas and Locks. Choose the site and then pick Not locked. Click on OK.)
Then, delete or change the site normally.