Can guests delete their own uploads?

Yes: a guest can delete any photo or video they uploaded themselves, from the same phone and browser they used to upload it, with the trash icon on the photo or by selecting several at once.

The page recognizes a guest's own uploads by the browser session, not by the name typed, so a guest cannot delete another guest's photos even if the two used the same first name. Nobody has an account, so there is no password to recover: a guest who comes back from a different phone, or clears the browser, is a new guest to the page and can no longer delete the earlier uploads themselves.

If that happens, the host can delete the photo instead: the host sees a trash icon on every upload and can remove any of them, one at a time or in a batch.

A deleted upload is gone from the gallery and from any ZIP requested afterwards, and it cannot be undone. Deleting is for the accidental photo of someone's shoe, so ask guests to look before they tap.