first of all tell us how old are you and let me get this straight basically you play games on your parents pc and you think they installed spy software on it ? i read your post 10x times couldn't make sense of it
problem : when I delete steam from my pc there still is a "steam" folder somewhere in pc but I cant find it in the search bar , where can it be? - thats the question. Whats the purpose of asking my age? it shouldnt be your concern at all my friend.
Maybe try to talk with your parents about you playing games, instead of being sneaky peaky like. Or buy your own shit and stop crying.