Open SMS link to another gmail account.

I have multiple gmail accounts. Initially I authorized the SMS page with the wrong account. Now I'm unable to switch the account. I tried to uninstall the extension and reinstall it and the issue is the same.

Any way I can switch the gmail accounts?

Thank you,

 

I can access https://joinjoaomgcd.appspot.com I cleared the cookies, and now I'm asked to authenticate when I access https://joinjoaomgcd.appspot.com/ . Once I select the account I can see the files in my gdrive. But when I try to bring up the SMS window the page is blank as in the attached image