Comment 13 for bug 1726922

On this page

https://askubuntu.com/questions/967137/calendar-constantly-requiring-google-authentication-on-17-10

a solution is suggested:

"I was having the same problem and resolve it by deleting the configuration files of Evolution. Do this:

rm -rf ./.config/goa-1.0/accounts.conf
rm -rf ./.config/evolution
rm -rf ./.local/share/evolution"

Worked for me