Samsung Tablet has been stolen and I have Firefox installed.

My Samsung Tablet was stolen from my hotel room a few days ago whilst on holiday. The tablet has security to login but I'm concerned they could bypass and get access. Can I block the device from accessing my Firefox Account (saved bookmarks, passwords). If not, should I just change the Firefox Account password and this should be enough? My concern is that I have just changed the account password on my laptop and I then accessed Firefox on my mobile and it didn't request login. The desktop bookmarks and passwords were displayed after clicking a bookmark.