There is no “right” age for a child to stop trick-or-treating. In reality, the majority of children lose interest in going door to door when they are about 12 or 13. Occasionally, you do get teenagers who enjoy it — but they are few and far between.
You are better off looking at the ages of trick-or-treaters in your area. Are they relatively young? Is your child going to stand out?
You should also consider your child’s excitement. Is he or she legitimately excited for the holiday, or is free candy the only allure?
If your child really does seem too old to trick-or-treat, establish a scary movie night or go to a haunted house instead.