Same situation. I thought I should take the subject tests even though they weren't required to try impress colleges... but I didn't study enough. I'm guessing my scores will be about average.
I'm applying to Scripps, Pitzer, UCLA, UCB, UCI, and UCM. Since some of these schools are kind of selective and I'm trying for scholarship, I'm worrying that mediocre scores hurt me more than help me. I've thought about canceling the tests, but since colleges see that (?), I'm not too excited. I'm pretty sure that we can't change our score recipients by the time we see our scores (Collegeboard would send them to colleges as soon as they're available, right? you can only change your recipients up to 9 days after the test).
So... is it possible to remove the schools from my score recipients /now/, then start the score reporting service after I see the scores (and still use the fee waivers)? That's the option I've been clinging to, but I don't actually know if I can do something like that.
I think schools will take your scores any time, unless the deadline or consideration period has already passed.