I agree that canceling your charitable remainder trust now would carry tax consequences, namely because you already received a deduction upon its creation.
Assets that are investments within the trust could be replaced by other assets more suitable (profitable) without voiding the trust agreement itself. That appears to be a more practical solution for you, assuming your problem is with the performance of the investments and not the trust itself. Look to your trust agreement too for any specifics with your personal trust.
Again, assuming your issue is of course the losses and not the trust itself, then you also need to consider that CPA's do not typically give stock tips on any sort of a professional level (they are not licensed for that in general). You would be leaning towards (full service) brokerage firms, investment advisory firms, and or portfolio management firms for advice as to "what should I invest in." The CPA told you how to invest (the trust) for tax purposes, but you are typically free/expected, as I said, to manage the income producing assets of a charitable remainder trust to the best of your (the trustee's) ability.
I'm sorry your investments did not pan out that well. Most peoples' did not, but many managed to make some money back too and may continue to here going forward. This may not be what you want to hear, but ultimately you must watch your own investments first and foremost, you need to hire the right person(s) for managing investments if you (like most people) want someone that is likely to do a better job than you, and finally, you need to make a rational decision now (your CPA may actually still be quite competent from what I can tell at this point, seeing as how many a (certified) financial advisor/planner/analyst/etc. lost money during the crash, and otherwise it sounds like you may have (had) some solid tax planning in place...).
Good luck. Thank you for your question and let me know if there is something more I can clarify.