Unless I'm genuinely embarrassed by the shitty production quality of my work and don't feel at all like cleaning it up, it stays up. For most cases, I define a failure as a story I can't complete in a way that makes me satisfied, IE it gets killed by bad planning or a lack of motivation.
I suppose I could also call a story a failure if it doesn't get any publicity, but I don't like dwelling on that kind of "failure" because at the end of the day damn near anything can find commercial success if sufficiently marketed, and posting my work online, on websites like Tapas, isn't exactly the pinnacle of advertising excellence...
And it's for that reason that I keep my backlog up. I mean, who knows? Maybe fans of one work will actually grow more attached to another, failed project of yours that you've had rotting around in the compost heap for a while, developing a cult following if/when you decide to revisit that idea.
Example: Monsters In Plain Sight is my very first work, and was planned to be way longer but I realized that I had no idea where I could take it in the long term, so I pretty much just clipped it off at what I felt would be a good stopping point. While I would consider it to be fairly crusty and rough around the edges prose-wise(At least, compared to my TRUE POWERâ˘), in terms of Bruce Anders' POV I absolutely adore it and I would love to either extend or completely redo this story later on down the line. For those interested, here it is: