cd C:\Program Files\Microsoft Visual Studio 10.0\Common7\IDE tf workspace /delete workspace;mydomain\myuser /s:http://server:port/tfs_instance_name A deleted workspace cannot be recovered. Workspace 'workspace;mydomain\myuser' on server 'http://server:port/tfs_instance_name' has 32 pending change(s). Are you sure you want to delete the workspace? (Yes/No) y
Typically the workspace has the same name as your machine.
Note: this is basically a repost from my previous blog.