To change timezone from command line therefore updating your date & time to a new/correct timezone, follow these steps.
Step 1: Check current datetime & current timezone
Check current datetime
date #output Fri May 24 18:45:26 +07 2019
Check current timezone
timedatectl
#output
Local time: Fri 2019-05-24 18:56:49 ICT
Universal time: Fri 2019-05-24 11:56:49 UTC
RTC time: Fri 2019-05-24 11:56:50
Time zone: Asia/Ho_Chi_Minh (ICT, +0700)
NTP enabled: yes
NTP synchronized: yes
RTC in local TZ: no
DST active: n/a
Check list of available timezone
timedatectl list-timezones #output (cut) Africa/Abidjan Africa/Accra Africa/Addis_Ababa Africa/Algiers Africa/Asmara Africa/Bamako Africa/Bangui Africa/Banjul Africa/Bissau Africa/Blantyre Africa/Brazzaville
Step 2: Update timezone to a new one
Using this command to do
sudo timedatectl set-timezone Africa/Bangui
You can check list of timezones with command above.
After setting new timezone done, your system date time will be updated automatically.