Can you delete a user without deleting the post?

I tried to do a search to find an answer to this question and could not. It seems that it would be somewhere in FAQ, or the forums but I had no luck unless I was asking it incorrectly.

I am building my blog and I deleted a test user and the post that this test user had were also deleted.

So my questions is, how can you delete users with out deleting the post?

SJ