There is no legal age limit for leaving a child on their own, but it's an offence to leave a child alone if this puts them at risk.
If you catch your teen sneaking out (or sneaking back in), enforce consequences that will deter them from doing it again. Instead of getting (too) mad.
At 10 I was watching other kids. It's up to a parent and that child to decide if that child is mature enough to stay home alone, some states have laws.
Here in the UK a 16 year old is deemed suitable to act as head of a household. If your teen is sensible then why not. You don't want to come home to a.
Two criminal laws specifically deal with kids who are left alone. One says that leaving a child “6 years of age or younger unattended in a motor vehicle for.