How to reset or delete your passphrase
Go to the Google Dashboard.
Click Reset sync.
Click OK to confirm.
In the upper right corner of the browser window, click the Chrome menu Chrome menu.
Choose Settings.
Sign in to Chrome. Sync will start again and you'll no longer have a sync passphrase. You can create a new sync passphrase by following the steps in the "Create a sync passphrase" section above.
If you’re signed in to Chrome with an account issued by your school or work, you may already be signed in. In this case, click Set up sync > Done.
Repeat steps 4-6 above on all other devices where you use Chrome.
Note: This will delete all synced data from Google’s servers and disconnect all synced computers and devices, but won't delete the data that’s on your computers or devices. Don't worry: you'll still be able to see your current preferences, bookmarks, and passwords in Chrome. You can start syncing again by signing back in to Chrome on your devices.