how can i delete my own thread?
You can not. You can delete your posts but can not delete your threads / topics. You only can lock your thread, move it to Archival or send a report to moderator and hope that they will delete the thread for you.
Just don't create threads so you won't have to delete them.
I search for answers from moderators in that thread but mprep will need to correct this Q&A.
Q: How do I delete/lock my own thread(s) when I no longer need them?
A: On the top right of your post is a delete button. You can delete threads if nobody has seen them. Otherwise, just click "Lock topic" link at the bottom left.