Is there anyway I can manually reset my iPhone 5s completely without using iTunes or passcode?

I need to reset my iPhone 5s and I don't have access to a computer right now and my cousin thought it was funny to change my passcode I can't just call him to get it so that's not an option. Is there ANY other way? Like any buttons is have to hold? Lol

Sorry to hear that, your situation is very common. Unfortunately there's no way to reset your passcode while on the go. Even connecting your phone to your computer will prompt for the password to access data. The only way to get this phone to work is to do a Factory Restore with a Computer that has been SYNCED with that phone. The computer stores some information related to your phone just in case stuff like this happens. BEWARE your DATA will be LOST, but you may restore from a backup.