How to edit / close a poll?

Is there a way to edit and/or close a poll? (E.g. when the options need to be updated, or the poll became irrelevant)

Yup. I have tried that, but there is no pencil icon. Perhaps this feature is disabled for regular forum users?
Here’s what I see:

The first post, not in edit mode:

After clicking the “edit post” at the bottom of the first post:

After clicking “go advanced” or “edit post” while editing the post: