How to delete win 10 administrator from predecessor?

I got my older laptop from my brother, (laptop win 10), is logged in (administrator microsoft), how do I delete the administator from the laptop to log in myself! Without predecessor administrator

You can eg reinstall Win10 and thus everything is nice and clean. Before check which Win10 version is used, eg. Win10 Home.

Alternative but not so clean, sign up for a new account with admin rights. Then delete the old admin account.