You’ve owned a project from the start. It’s taken energy, effort and time and you’re invested in it. It doesn’t have to be a full-blown activity, it might something relatively innocuous like a blog post.
But it’s not going to achieve what you wanted it to. Your sponsor has cooled, the spark of need has dulled. Your motivation for producing it has waned and it lacks validity.
Make the decision and stop. It doesn’t deserve your energy any more.
But you’ve not lost; the experience you’ve had creating it is your win.