Deleteing threads

I am just wondering how I can delete the threads I posted?
I think I should delete them..

You can't delete threads.
The whole point is to allow people to continue to learn, contribute and make corrections to an ongoing discussion.

If you could just delete the whole thread as soon as you have an answer, then that pretty much makes the whole exercise pointless.

Oh, FWIW, if you just want to abandon your thread before there are any replies, then just do what you did, and a mod will clean up at some point.