How to clear Google photo authentication?

[Mark S. (DK)]

I apparently set up a previous authentication with Google Photos. Now 
when I try try to use it, I get a "This site can't be reached" message. 
I assume that I need to redo the authentication process. The problem is 
that DK won't let me delete the existing authentication -- it wants to 
log off, which it can't do because it thinks the site can't be reached. 
So I'm caught in a loop. What I need is the ability to delete the 
existing authentication and start over.

Thanks!

Digikam 7.1.0, Linux