In legal terms, the executor of a will is a “fiduciary.” This means that the decedent placed his full trust in this individual to protect his estate after his death and to disburse his property to his heirs according to his wishes. When the court accepts the decedent’s nomination and appoints the executor, the court is also putting its trust in him. When an executor accepts office, he takes an oath that he’ll act in the best interests of the estate and won’t do anything to cause it harm.
Acting in the best interests of the estate does not mean that the executor must always be polite and civil toward the decedent’s heirs. It means he can’t cause them financial harm. If the executor is openly hostile toward you, but he does nothing to financially harm the estate, you usually cannot have him removed on the basis of his hostility alone. However, if he takes his hostility one step further and deliberately handles the estate in such a way as to cause it -- or you -- to lose money, you might have grounds to ask the court for his removal. For example, he might move estate funds from a safe savings account to a risky stock investment while the estate is in probate, knowing that if he loses the money, there will be nothing left for the decedent’s heirs to receive after the estate’s debts are paid. This sort of behavior qualifies as fiduciary misconduct, which you can use as grounds to have him removed from office.
Removing an executor from office involves filing a petition with the probate court, asking a judge to terminate his position. You must have “standing” with the estate to file this type of legal action. This means you’re either the decedent’s heir, so you would have inherited from him even if he did not leave a will, or you're a named beneficiary under the terms of the will. After you file your petition, the executor has a right to defend himself, so this generally results in a court hearing. You must present evidence to back up your position, and when you’re dealing with a hostile fiduciary, this is a twofold process. First, you’ll need documented proof of his hostile actions. This might involve witnesses who can testify to his behavior toward you or other heirs or beneficiaries. Then you’ll also need to show examples of his misconduct. You’ll need documented proof of transactions he made or actions he took to deliberately cause you or the estate harm.
If you file a petition for removal and you don’t win, you might make the situation considerably worse. You already had a contentious relationship with the executor, and now he probably has even more hard feelings toward you -- and he still has control over the estate. If you find yourself dealing with a hostile executor, confer with an attorney to make sure trying to have him removed is worth the risk. If he isn’t really doing anything to harm the estate, you might be better off allowing probate to run its course. The estate will close eventually, and your relationship with him will end.