Once you make a post, on the bottom left side of your post are three boxes, report, edit, delete. Click delete, provide a reason for the delete in the popup box and confirm delete.
Deleting a THREAD that YOU started is done (if I remember) by going to the top of the whole thread and you should see the some type of affair, like the one I explained for a post or there may be a “more actions” or SOMETHING there.
My total BAD... it’s not an Edit button, very sorry. It is (on my phone) to the right of the “!report” button...a small box with “...v”, more options will drop when this is clicked. Hope that sets up right real sorry my mistake.