Two kinds of expiring link
An expiring link can end in one of two ways. It can end after one view, which suits a password or a note: the first reveal destroys the stored copy and the link is dead from then on. Or it can end at a date and time, which suits a web address you want to share for a while: a signup page for an event, a draft for review, a download that should not live forever.
The creator above handles the first kind as a secret and the second kind as a short link; switch tabs to pick. Both are free and need no account.