How to access host page / booking.com extranet as a co-owner and co-host?

I recently have become a co-owner and co-host of two guest houses. I would like to have my own access to the host pages  to set up changes or edit texts, upload pics and communicate with the guests without depending on my partner as we share everything. How does that work? What must I do? 

In my attempts I opened a total new host page under my name which I would like to deactivate again. However it is not possible as it does not give me the link button but only the one to log off.

Thanks for helping / answering my questions.