To be on the safe side, it should be "revoked" in writing by both of you in front of a notary. Anyway, it really should only be revoked with another trust or a will. Either way you want a lawyer to help you. Contact a lawyer who answers your question here or find one on avvo.
I think revocable living trusts are a very good idea however having a joint revocable living trust is usually not recommended. I would go to an estate planning lawyer and get this fixed. The reason a revocable living trust is a very good idea is that it can really help manage your assets when you or your husband becomes incapacitated. These planning devices are not just to direct your property when you die, it is also for lifetime management as you and your husband age and need third party assistance. This way of planning is not for everyone however. It requires some ongoing maintenance to make sure you are managing your assets so the assets are properly held by the trust, otherwise the entire reason for having a revocable living trust is defeated. When property set up and maintained the revocable living trust can save your estate thousands of dollars that would otherwise be spent on attorney fees setting up a conservatorship for a disabled spouse or doing a probate.
As to your immediate question, it is a very bad idea to try to simply cancel your trust. If it was set up properly, then you have assets that were transferred into the trust and you will create a big mess if you start trying to come up with your own creative ideas. Make an appointment to see a probate attorney, figure out what if anything you need to do, and do it properly with sound legal advice.
Also, keep in mind that a Will may not necessarily control how your property passes when you die. It is a bit more complicated then that. You can only be certain that things will work the way you intend them to work but getting sound legal advice and following the attorney's recommendations.
The termination of a joint revocable trust by the persons who created the trust (the settlors) is called a revocation. When you created your trust you probably signed a written trust agreement. Your first step should be to read your trust agreement and find out what your agreement says about the revocation of the trust by the settlors. ORS 130.505 also includes provisions regarding the termination or amendment of a revocable trust. Revoking the trust is not the whole problem. Even if you properly revoke the trust there may be assets titled to the trust, trust accounts and other loose ends that need to be addressed. There is also the question of what kind of estate plan you do want if you no longer want a revocable trust. I encourage you to consult an attorney experienced in Oregon trust administration law and Oregon estate planning law to work through your situation and develop your best options.