My most recent one actually lol. It's not that I didn't like it, it's that I anticipated it only being a one-shot but it ended up needing to be longer. The reason it's a problem is because I had three other chapter fic ideas that I was more excited for.

I kept writing it but by chapter four I felt like I was rushing it and let my readers know that I'm putting it on stand-by for now.

This hasn't happened to me, but I think I'd just drop the story. Though I guess it also depends on what you're regretting. If it was something like losing interest in the idea I'd just drop it, but if I realised something I disliked in the story's contents, some sort of implication or something like that, I'd be more likely to want to delete it.

^It's personal reasons and though I liked writing it I can't bring myself to continue.
And now I'm getting reviews that say 'Update?' or 'Gee, I guess this story's finished, now!" and I don't know what to do.
It's like looking at a never ending math test. It's not fun anymore.
But if I stop I'm afraid of backlash.

In that case, I'd stop writing it, and explain that it's been stopped for personal reasons in an author's note. Most readers will understand that.

^I think I'll do that. Besides I can always save the story and repost it when I feel ready, again. Thanks for the advice :)