It could hurt your chances, but you could still become a police officer. Right now getting police officer jobs is usually very competitive. Any red flags can cause some employers to go straight to the next candidate. Police departments usually have many qualified applicants for a relatively few openings. It is better that this occurred when you were a juvenile as opposed to an adult, and it is better that that occurred 5 years ago as opposed to more recently. Definitely do as you wrote, and be honest about it.