Issue while creating an Environment

Hello everyone ! For one of my course I am required to create a new environment. The navigator used to be working just fine but this time it is impossible for me to get it work. Every time that I am trying to create an environment I get this error message:
UnavailableInvalidChannel: HTTP 404 NOT FOUND for channel gurob

The channel is not accessible or is invalid.

You will need to adjust your conda configuration to proceed.
Use conda config --show channels to view your configuration’s current state,
and use conda config --show-sources to view config file locations.<br

From what I understand, my current configuration needs to be changed, how to I remove something from it ?