I say Yes to delete my own Posts. and I have often deleted my posts, and here is why:
1. It is off topic, or a bad joke
2. My complete post is quoted many days later ,
so it is better to have my post along with the response together in the later post.
3. A Group of members agree that a series of post are off topic or desire a new topic
and wish to repost in a New Blog topic
4. I wish to be able to delete my post when it was incorrect
and someone has posted a more correct response ,keeping the blog clean
5.. Right of Copy
I once cleaned a large Blog of my unnecessary posts and reduced the Blog 5 pages;
so I BS a Lot
I agee the first post (the topis) should not be deleted,
but maybe allow it to be unassign who Posted it