Plans change. You can update your RSVP right up until the event ends. Once it's over, responses lock in and the event shows a Past badge.
If the host set an RSVP deadline, you'll see "RSVP by" on the event. After it, you can still switch to Can't go, but you'll need to ask the host if you want to change to Going or Maybe.
If you have a PopIn account
Open the event page
From your notifications, your profile, or the event link directly.
Tap your current response card
It's at the top of the event page, showing your current RSVP.
Pick a new response
Going, Maybe, Interested, or Can't make it. The change is saved immediately.
If you RSVPd as a guest (no account)
Open the same invite link you used the first time. It always works. Update your response on the same page.
Going to Can't-make-it close to the event? A quick message to the host alongside the RSVP change is appreciated, especially for small dinners or events where the host reserved a table. Not required, just polite.
What hosts see
Hosts get a notification when you change your RSVP, but the alert is low-key and doesn't include any commentary. They just see "Alex updated their RSVP to Maybe". No reason field, no shame.
Plus-ones when you downgrade
If you had a plus-one added and you change to Can't make it, your plus-one is automatically removed too. You can re-add them if you change back to Going.
Reminders
Once you switch to Can't make it, reminders for the event stop automatically. You can still open the event page (and any post-event photos or memories) via the same invite link.