Is there a chance to delete Work Item from TFS, or all I can do is just to rename it.
Update: This question was for TFS 2008. New version (2010) have out of the
See this tool: http://devmatter.blogspot.com/2009/04/deleting-work-items-in-tfs-ui.html
the Team Foundation Client does not include any functionality for deleting work items from TFS.
Although it’s a tad inconvenient, you can delete work items from TFS by installing the Team Foundation Server Power Tools (October 2008 release or greater). Of the many features available as part of the power tools, there is a command called destroywi that can be used to delete work items. For example, to delete the work item ID 1234, use the command:
tfpt destroywi /server:tfs-dev /workitemid:1234
Although this is a relatively straightforward task to perform, not everyone is comfortable with the command line interface not to mention you have to look up the work item ID(s) ahead of time. To ease the process a little bit, I created a simple UI that sits on top of the Team Foundation Server Power Tools that allows you to easily select a Team Foundation Server and Project to query from. You can run an existing query to display a list of work items from which you can select one or more work items to be deleted. You can also enter the work item IDs directly (as a comma-separated list) if you prefer...