Hi 

There are multiple ways to activate debug mode. 

1. You can activate Google Chrome Extension which allows users to activate debug mode.

You can search for Odoo Debug and Add it to your Chrome

2. Go to Settings --> Scroll Down to the developer tools section

3 . Add "/web?debug=1" to the end of your Odoo URL. For example http://your-odoo-url.com/web?debug=1

Regards