You will find the information easily, and it seems very simple: in your template, just do:

{% if not debug%}I'm in debug mode!{% endif%}

This won’t work, this is not enough!

In your settings.py file, you must configure the IP’s correctly, which specify that you are / or not / in “development” mode:

INTERNAL_IPS = ['127.0.0.1',]

(Note that this code can be optimized in a way that depends on the environment, for example I made a settings.py which takes this into account).