Note that I'm not a forum wizard and I'm just going off of something I read somewhere. I might be wrong.
I think you can, but it only works if that was the last reply posted. Obviously you also had to post that comment.
For example, if User A posts a reply and then User B posts one, that post will not be delete-able. Similarly, if User A double posts (which is apparently frowned upon) then only the newer post can be deleted. However, if no other replies were posted then you probably can delete it.
You shouldn't really delete posts nonstop. If you made an error or want to append it with new information you should edit it instead. Also, your project's thread only seems to have the original post; maybe the reply you posted was automatically merged?