How

It appears you have only posted this thread and reply with this https://support.mozilla.org/en-US/user/haselmorazan/ Mozilla Account.

If a thread has not been locked by being Archived then you can look at top right besides the post for Question Tools > Edit this question. To edit a reply click on the vertical three dots on right of reply and Edit this post.

You cannot completely delete your own thread or replies and we generally do not delete any threads or replies here. We can hide the thread or reply from public but that is normally only done for spam and such.

I commented on a question, then realized, that I probably should ask the question, myself.

I did not post what I wrote. However, after I did post my question, I found the comment posted as a question. So I wanted to delete it, having streamlined my question, instead of it being a total rant. The only thing I could do is delete the content - after I did post the question I did ask (instead of it being a comment to someone else's question).