I had a friend listening on my profile for months, and now i got my profile back so i would like to erase all my data and start again (so i dont have to delete my profile and make another, because i use the student discount), can i?
There is no option to delete all your account history that I know of. You would need to create a new profile in order to start truly fresh. But as you noted, the student discount is locked to your profile for the full 12 months.
My best recommendation is to keep playing music you like and give feedback to Spotify through certain playlists (Daily Mix, Discover Weekly, Radio stations) so that it can adapt faster to your own listening taste. Have a great day and happy listening! 🙂