What do you mean they were installed
Is this a legit switch, and someone sent it to you with his account on it and this games installed?
Dude just got his account unlinked from your console, probably forgot to do it before, and now you can't access the games anymore. Naturally, cause you didn't buy them and they're not on your account.
If I give you my Steam login data, and you play games with my account, and then I change the password so you log out, you won't be able to access them anymore. Kinda the same thing.