My Brother has passed away. He has a MacBook Pro that I would like to change the Administrator to my name. How do I go about doing that

Do you need access to all of your brother's old files, or would you be OK with just wiping the whole drive and operating it as if it were a factory reset computer? It's pretty easy to just wipe it and start over from scratch, but to gain access you're going to need to get help from Apple.

If it's one of the older MacBook Pro models with a SATA drive, it's easy enough to just remove the drive (to just store as is) and start over with a new drive. The latest models (starting around 2010?) allow formatting and OS installation with just an internet connection and don't even require a working operating system or install discs to do that.

I'm sorry for your loss ...

If you can, take the Mac to an Apple Store along with a copy of the death certificate.

Changing ownership of a used Mac | Communities

You will need to go to an Apple Store with the following documentation:

1. Your brother's death certificate

2. Proof that you are entitled to the computer. (Typically, a will or other notarized document naming you the executor of his estate)

3. Proof that he owned the computer. (Typically, the original receipt or a statement from the Apple Store where he bought it or from Apple if he purchased it online.)

4. Photo ID proving that you are who you say you are.

If you are able to gain access to the computer, please be aware that you will not be able to access your late brother's Apple ID account. That account and all of its contents will be removed from Apple's servers.