GCP Wordpress files directory permission using sftp

I am trying to upload (modify, edit, delete) files to the directory with Wordpress using Filezilla, but the file directory does not have permission to write to.
I have this mistake

/var/www/html/Nouveau document texte.txt: open for write: permission denied
File transfer failed

Capture.JPG Capture.JPG


I am not sure which user you tried to login. Basically the default user and owner are by web user (usually is www-data on Debian system).
So you can make the www-data user has the bash permission and login as www-data user to update the file (This might has potential security issue to make www-data has bash permission)
or `chown /var/www/xxx/xxx` to www-data:USER-NAME and `chmod to 775`(default is 755)

or just upload files to /home/YOUR_USER/ folder and then SSH as root user to modify the file.