While working on customizing the My Site default layout, I found that I needed to be able to delete my My Site and have it recreated from scratch.
So far, the way I've found to do this takes 2 steps.
First, delete the contents of My Site:
Go to My Site
click the "Modify My Page" dropdown link
click "Reset Page Content"
- note: if you do not see a "Reset Page Content" link then no content change were made so you are all set.
Second, delete the site collection:
Go to the Windows SharePoint Services Central Administration
click on "Delete site collection"
enter the site in the following format: