You can access to phpMyAdmin after creating ssh tunnel.

How to Set up SSH Tunneling (Port Forwarding)

ex.) create ssh tunnel

$ ssh ubuntu@{ipaddress} -i {ssh-key-file.pem} -N -L 8080:localhost:80
http://localhost:8080/phpMyAdmin

For phpMyAdmin please refer to phpMyAdmin User Guide

Reference

• Ubuntu
• phpMyAdmin User Guide
• How to Set up SSH Tunneling (Port Forwarding)
• GCP General purpose machines