I let some friends borrow it at the park but i never let them keep it over their house or anything, a couple times i've let people use it they've dehubbed my wheels or broken something.
But if you don't want them using it just say your parents won't let anyone ride it or you don't want it to get messed up.
i let the cool(non-gay)/Good skaters ride my scooter
i dont cos this one time at band camp i let somebody on my scooter and then they gave it too this guy and then he rode off with it but then i ran after him and pushed him into a bush and got it back