You can clear your history in Shift by completing an app data reset. Resetting your app data will clear away the data that's stored locally on your computer that keeps you logged into your accounts in Shift. This means you will need to log back into your accounts again, but your setup will remain intact.
WARNING: Any opened or pinned web tabs that are not saved as Bookmarks will close when you reset your app data. Read more about that here.
Click options (lower left) > Settings > General
- Scroll to the very bottom of the page to find 'Reset App Data' tab
- Open Shift. Log back in with your primary account
Learn more tips and tricks here.