Macbook Pro User Difficulties

I have a macbook pro mid 2012 running on catalina 10.15. I was gifted this laptop after they got a new one, and ever since i have been finding little traces of them. I did not do a factory reset because i guess i have to get a disk for it? I dont know. But i figured out through googling how to go through the files and get rid of of all the hidden caches. The only thing left is the home file. I tried creating another user admin and renaming the file, but my computer just creates a new user folder that doesnt go with my account. What is the right way to do this? Am i missing a step? Please help. Also after i created the new admin account and logged out of my original, before logging into the new account, the login screen popped up that required me to type a username and password. I couldnt get the name right for the new account so i turned the mac off then on. Once i logged in to the new account and switched back to the new one after trying to rename the file, i noticed that EVERYTHING got transferred to the new user account. Does anyone know what the happened? Is my mac being hacked or do i need to fully reset my laptop? Thanks for the help!