An executor cannot make changes to a will. The executor is bound by law to carry out the provisions of the will and has no authority to make any sort of alteration to the will's terms.
According to Caring.com, the duty of the executor is a simple one: to carry out the wishes of the deceased. The executor is tasked with handling the decedent's assets and taking care of the decedent's debts and then transferring assets to the heirs as named in the will. Executors are expected to act with honesty and good faith on behalf of the deceased, not to make any choices about asset distribution.