TFS cannot delete work item ?!

Today, I helped the customer create an account and found that the work item used for testing cannot be deleted (I tested it with a bug... the result is very embarrassing), but it can only be closed. I checked msdn and found no relevant instructions.
I checked it as a tool. I know that Ms prefers to put this function in a very humane place.
I can only Google it. I saw someone posted an SQL statement on the MS Forum, suggesting that this SQL statement can eliminate the workitems created by mistake. I am even more embarrassed...
Some time ago, I was very happy to install tfs2008 on server 2008, and port 80 exists with SPS, SRS, and tswa (the error is not found in the log at last ...). This reverse proves that I just made a beautiful garlands on an embarrassing system...
I was struck by lightning.

Postscript (): After downloading the power tool, I found someone's blog pin such a shocking story.

How to delete a work item type on TFs.

You can delete a work item type on TFs 2008. You'll need to use the power tools: http://msdn2.microsoft.com/en-us/tfs2008/bb980963.aspx. There isDestroywitdCommand.

I used to find the source of Ms again.
OverviewThe Visual Studio team System 2008 team Foundation server power tools is a set of enhancements, tools and command line utilities that improve the team Foundation Server user experience.

The following tools are installed with this package:

• Command line tool (tfpt. EXE)
• Team explorer ide menu additions
• Build notification Tool
• TFS best practices Analyzer
• Process Template Editor
• Work Item templates
• Custom check-in policies

Someone is very powerful, and he gives me confidence...
Ms puts powerful tools on the website for free download...

Postscript:
The correct tfpt. EXE command line for deleting workitem is destroywi.