Q: How can my mother can remove her husband as executor for her individual trust and designate me instead?

A: The person who is in charge of a trust is a Trustee.

The person who is in charge of a will is the executor.

The executor's job does not start until the person who wrote the will passes away.

Since no-one has passed away, I believe that what you are talking about is REMOVING A TRUSTEE.

The answer to that question depends on what the trust says, so there is no way anyone can give you that information without reading your trust. Start by reading the trust. Read the section that talks about removing trustees. See if it is allowed. If your stepfather has dementia, it may be possible for him to be removed as co-trustee by a doctor writing a letter stating that he is no longer able to handle his affairs. You also need to read the trust for the procedures for a doctor to make such an evaluation and write such a letter. Trusts are not all the same. You would need to make an appointment for your stepfather to see his doctor for the doctor to evaluate him to be able to write such a letter. Call the doctor's office and find out if they doctor is willing to evaluate your step-father on Zoom, or Skype or Facetime. If the doctor will do that, then you can get your letter. But before the doctor writes the letter someone needs to read the paragraph in the trust as to what the doctor exactly needs to say in the letter.

There are a lot of "ifs" here. If your mother and stepfather are co-trustees, and if the trust allows your stepfather to be removed as one of the trustees by a doctor's letter, then your mother would be the remaining sole trustee. Then if your mother no longer wants to act as the trustee, she can resign. That resignation needs to be in writing and notarized. Then you read the trust and see who is the next in line as the successor trustee. Is it you? If it is you, and she resigns, then you become the trustee. If it is someone else, then that person becomes the trustee. One way to do it, is for all the trustees ahead of you to resign, leaving you as the trustee.

Another way to get to the point where you can be the trustee, is to read the trust about AMENDMENTS. Amendments are changes to the trust. Also you need to read your trust to see if amendments by one trustee, your mother, are allowed, or if it requires both your mother and stepfather acting together. If your mother is allowed to change the trustees by Amendment, then usually it means that she can change the trustee to you. It needs to be done in writing and notarized.

Attorneys who prepare wills, trusts and estates can prepare a letter for the doctor to sign if that is needed. They can prepare a letter for your mother to resign as trustee if that is needed. They can prepare an Amendment naming you as trustee, if that is allowed under your trust if that is needed.

Some attorneys offices will also allow your mother to talk to the attorney by Skype, by Zoom or Facetime without having to go into the office, and then prepare the documents needed and send them to you by email or snail mail.

You can pay them by check, Venmo, PayPal, $CashApp, Zelle, and other payment methods depending on what they use in their office. Any attorney who does Wills and Trust in California can prepare these documents. It is not necessary to go back to the attorney who prepared the documents. It is also not necessary for the attorney to live in your city. The only thing that is required is that the attorney must be licensed by the State Bar of California. You can check out any attorney with the State Bar at this link: http://members.calbar.ca.gov/fal/LicenseeSearch/QuickSearch?ResultType=0&SearchType=0&SoundsLike=False. Or you can just Google: "Attorneys State Bar of CA."

I hope this answers your question.

A: If it is her trust, then she probably has the authority to fire the trustee. You have to read the trust.

A: It depends on if it is just her trust or her trust and his trust. If it is their trust together then they probably need to do an amendment if they have the capacity to do so. Also, they can just sign a resignation of trustee if they have the capacity to do so. If they do not have capacity, then you should be able to get a letter of incapacity for both of them and if you are next successor it would go to you.