I don't think you can Close/Lock, delete or remove your own Topics, if you are the OP, but there is surely an option to EDIT the thread on the Top right corner. Only an ADMIN, STAFF member and Forum MODs can Lock/close any Topic, or even delete them, IMO.
For awarding others the best answer under your own Topic, please go through this Link. Are you asking about this, or some other thing ?
This post is replaced with - https://forums.tomshardware.com/threads/how-to-mark-posts-as-solved-award-best-answer.3803582/ The means by which a Best Answer is awarded has changed since we moved from old forums to this brave new world. If you are the thread opener, you have a choice in the...
forums.tomshardware.com
As a side note, BTW, I have the option to delete my own thread/topic which I posted recently under this "
Forum Rules & Feedback " section. But I don't get to see this option on my other Topics posted under other Forum categories/sections (PC Gaming, Graphics cards, CPUs, etc).