Hi Susan can you please confirm that you followed these instructions to disconnect?

To disconnect your tracker, please follow these steps on grokker.com.
Please note this cannot be done on the Grokker app.

Click the profile icon on the top right corner of the page and select "Account Settings".
On the left hand side of the page you will see a section "Connect Accounts".
Select the "Disconnect" link for the account you would like to disconnect from Grokker.
The tracker will be disconnected from Grokker, and you will now see the link to connect to the device account.