Delete Blog

Try this:

 Go into the window to edit it, and click on the HTML button:

Delete all the text in the window that pops up and save. That should do it.

If you don't have the HTML button, you should!

Go into your Forum Control Panel and change the  "Use rich edit box when composing messages?"
Setting to TinyMCE and you'll get a toolbar with all kinds of cool formatting commands in your blog, and in the forums.