Do I still need to wear facemask after vaccination?

Yes, you are advised to continue to practice the preventive measures – wear your face masks, frequently wash your hands with soap and running water or alcohol-based hand sanitizer, observe physical distancing and avoid large gathering and unnecessary travels to stop community transmission of COVID-19.
This is because getting the vaccine does not stop you from getting exposed to someone who has been infected, but the vaccination and development of immunity will stop the infection from progressing to disease – hence you still need to practice the preventive measures.