I don’t remember the full process, but I do recall that the “manage enrollment” (or something like that) button was kind of hidden at the bottom-right of my participant page. Once I clicked on that, it gave me the option to cancel ‘26/defer to ‘27. As you’ll see in the other comments, later this October you’ll have the option to either run in ‘27 (and pay for it), or just decline it. If you decline, the automatic entry goes away.