>>82973307
I don't think there's anyway to clean that sort of mix and extract only the MDMA. But considering Bath-Salts are a blenket term for a variety of synthtic Cathinones that should add to the stimulating effect of MDMA and are relatively safe on low doses, and Meth's not that bad, especially in lower doses too, so you might be able to get some value out of it yet.
So the answer is: providing you still are interested in using it, take less than you'd use normally (like 15-30mg max to start with, it's safer to be on the lower side of this range), in theory it should balance itself out, having the additional substances fill-out the spot for some of the main effects of the MDMA in it, if preasent at all that is.
Otherwise, if you're adverse to using a cut and diluted product, dump it all in the toilet and forget about it.
I say better safe than sorry, as you don't really know what's it cut with (it could be an unknown RC or some other drug that's completely different from Meth or Bath-Salts in effects and possible health risks), but it could be worth the risk with a little bit of experimentation to check the potency and look for any negative side-effects that might come-up; if, say, you experience too fast or too slow of a heart-rate, any internal organ pain, a bad/uncomfortable feeling, or similar effect on a low dose, it means you shouldn't take anymore of it or risk some serious health issues. In this outcome, the best-case scenario is you detoxing in the ER for a few hours then released sober and healthy; worst-case, you'll simply die of organ failure/an unintentional OD.
Personally and honestly, I'd risk it and dose-low to start instead of flushing it, but that's me and my druggie/economical way of thinking. I'd try to make it worth the cash-spent on principle, even if I'd be risking it a little in the proccess. In other words, I'd personally get high off whatever it is anyway.
Your choice in the end, I hope you make the right one.
Goodluck and have fun!