If I create an extra Windows account, but have previously signed in with someone else's account, will that person also see my new one?

So I don't know if I expressed the question clearly enough, if not again in detail:

I bought a laptop a year ago and the first account I signed in with was someone else's. So that's basically the administrator account. Now I've made my own and now have access to both. Now the question is, can the person from the other account also access my own? So without a password?

All members of the admins group can do this