Change account name

In System Preferences , Users & Groups, Control click (right click) on the account name and you will get the option to go to Advanced Options. In there, see what the Full Name says. If it says Admin's Macbook Pro, you can change that to your own name. Do not change anything else. You have to restart the computer.

Read the warning in that section and make a backup you can restore your Mac from in case something goes wrong.

Are you sure you want to change the account name, and not just the computer name?

To change the computer name follow the advice given above by Luis.

To change the user account name you have to go through the process given in the Apple Support link above.

DON’T change the account name.

Go to System Preferences->Sharing and change computer name.

Hi again,

Better do it the way Apple suggests. You still need a backup.

Change the name of your macOS user account and home folder - Apple Support