Can siblings take away another sibling from being executor of mother's estate?

First, I need to clarify some terminology. An executor is the person designated to handle the financial affairs of a person who died with a will. A personal representative does the same thing for a person who died without a will. Because you used the word executor, I'm going to assume that your mother died with a will. If one sibling has been named the executor of your mother's will, and the other siblings do not believe that sibling is qualified for an ethical or legal reason, the siblings may file what is known as a will contest to disqualify that named executor and have someone else named as the executor. There are specific reasons to disqualify someone from being an executor, and it's a good idea to seek counsel from a local attorney for more information about how to proceed.

An executor can be removed for cause by filing a motion in the probate court detailing what the executor has done to deserve to be removed. The executor will be able to respond and a hearing will be held to review any evidence presented. If wrongdoing is proved, the judge can remove the executor.