Deleting camera access from previous user

Can the previous email account associated with the Roku camera gain access to the camera again? How can you delete their acces? I've changed my phone number, different wifi, and a new email but I feel they still have access to their old email that was linked to the camera. And once I reset it with a new email and phone number and wifi, does that necessarily mean only "I" have access to  the camera or does thus person still do also? It's creeping me out Roku, y'all better fix this if that's the case.