Vendor folder inside public_html folder

How to manage update of dependencies inside public_html/vendor If I click composer install it will be via terminal from root. As it is vendor folder inside public_html, I have an issue as command scl enable ea-php70 'composer diagnose' will install inside ROOT. How to manage installation and update inside public_html/vendor not inside root using a command. Will this work a command from root? composer install -d=/home/public_html/vendor