The department posted to Facebook Friday to say, "It is with heavy hearts that we say, Officer Myles Timothy O'Connell-End of Watch 12/19/2018."
Myles was just a normal kid from South San Jose until he was diagnosed with a brain tumor in October 2017.
RELATED: 7-year-old with brain tumor gets wish to be Sunnyvale police officer
He had a love for boating and fishing, but what he really wanted was to work with his uncle who is a Sunnyvale police officer.
The department made his dream come true last March when they swore Myles in as an honorary officer. There was a full ceremony and Myles got to shake hands with every officer in the room.
Thursday marked his End of Watch.
"Officer O'Connell, you are a true warrior who fought a good fight against DIPG. Your battle is now over, but your fighting spirit will live forever and it will be engrained in us all," the department said.
Myles also received honors from the Folsom Police Department.
Just a few days ago, Folsom officers paid him a special visit.
They posted this video on Facebook, saying it was an honor to meet a true hero.