There are a few ways that someone can change an irrevocable trust; the easiest way is when the beneficiaries and the grantor of the trust agree to the changes. The grantor must be alive at the time of modification. This is called modification by consent.
Another option to modify an irrevocable trust is a modification with the court's approval. This option is used when the grantor either cannot or will not consent to the modifications proposed by the beneficiaries. A decanting, or distribution of trust assets, is another option. This provides a trustee with the power to modify an irrevocable trust without the involvement of the courts or beneficiaries.