A couple of options, you can reset the secret phrase which will delete the details on the Sync servers allowing you to start over again. For details of how to do that see the [[Firefox Sync is not working]] article. The secret phrase should be stored in the password manager of the Firefox version that you originally set up Firefox Sync with. Open the Options/Preferences dialog (for Windows, in the Tools menu select Options). In the Options dialog go to the Security panel and click on the "Saved Passwords" button to open the password manager. In the password manager click on the "Show Passwords" button and in the search field type '''chrome''', that should show your secret phrase.