Is it normal to trick or treat as an older teenager?

It depends how, what time, and who you're with. There's a big difference between "ironically" trick or treating at 15 with a bunch of 15-year-old friends to try to get some easy candy before a Hallowe'en party, and trick-or-treating with your mom as a 17-year-old before going to bed.

YES!

Everyone does it in my area like I don’t see the big deal when u get older like it’s the best night of the year (:

The last time I did it was when I was 13 or 14, I was one of the last in my year to stop though. There's nothing really wrong with it though to do it when you're even older, you just might get a lot of funny looks.

As long as you're not being troublesome!

Define "older teenager."