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Generally, when the testator dies, a revocable trust becomes irrevocable.
However, if you have a trustee that is not faithfully executing the duties of their position, as the beneficiary you can sue them for breach of contract and breach of fiduciary duty. You can ask the court to appoint a new trustee in this situation.
Depending on the specifics of your situation, you may be able to petition to have the trust dissolved, but this would be extraordinary relief, I would highly recommend speaking with a local trusts and estates attorney to discuss your matter in further detail as these cases are highly fact dependent (outside the scope of an internet "Q&A" general information forum such as this), you can find local attorneys using the State and local Bar Association directories, or private directories such as www.AVVO.com; www.FindLaw.com; or www.Martindale.com (I personally find www.AVVO.com to be the most user friendly).