How to get there: Click the portal switcher at the top of the sidebar (shows your current portal's name and favicon).
If you're an admin on more than one ProductLift portal, the sidebar has a switcher that lets you jump between them in one click, without logging out. Portals you've linked are remembered per browser so switching stays one click on every subsequent visit.
Once linked, the portal appears in your switcher list. Linking is one-time per portal per browser.
Click the portal switcher and click any linked portal in the list. You land in that portal's admin, signed in as your admin user there.
If you're in the middle of something (editing a post, viewing a specific board), the switcher preserves the intent path where possible.
From the switcher popover, click Manage linked portals. This takes you to your profile edit page, where you can see:
Revoking a link removes the trust for this browser. To use the portal again, you'll need to re-enter the admin password.