Once the pre-configured version is setup and running, how can you clear all of the content to start fresh?  I am trying to delete them one at a time, but keep getting this error on some of the items.

DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 706479b1-fc3a-479f-a30a-cc9fb1d6233d
InnerException: Nullable object must have a value.
FileName: 
FileLineNumber: 0
FileColumnNumber: 0
Method: System.ThrowHelper.ThrowInvalidOperationException
StackTrace: 
Message: DotNetNuke.Services.Exceptions.PageLoadException: Nullable object must have a value. ---> System.InvalidOperationException: Nullable object must have a value. at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource) at System.Nullable`1.get_Value() at System.Nullable`1.op_Explicit(Nullable`1 value) at Vivo.Modules.VivoIndexItem.EditIndexItem.LoadItem() at Vivo.Modules.VivoIndexItem.View.Page_Load(Object sender, EventArgs e) at System.Web.UI.Control.OnLoad(EventArgs e) at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---