What do you want to do? Change from standard to admin user? That has to be done by an admin.
This is Users and group. Here I could give mye son admin rights.
Do you want to change the name of your macOS user account and home folder. If so, that's quite easy. Right-click on the user and chose advanced settings
https://support.apple.com/en-us/HT201548
If this does not fulfill your needs, there may be additional things you can do in the Unix shell (Terminal).