Multiple client sites that all use the same login

[walshd001]

Hi, 

I have dev'd sites for 2 different clients and for some reason the login deets for Client 1 need to be used by Client 2. As a result all of Client 2's info from the backend gets sent to Client 1!

It says to do anything it says to contact Client 1 to make any changes. If i go into Client 1 (who is owner now of about 4 of my sites, wrongly - my fault completely) can i just remove from Client 1's Shopify ID? If i do that can Client 2 still log in? 

TIA