I brought an used Roku to it has the other person info. Is there a way I can sign them out so I can sign myself in.
Do a factory reset. On my separate Roku device the menu path is Settings > System > Advanced system settings > Factory reset. I expect it would be the same or fairly similar on a Roku TV.
You'll then need to set up the set as though it were brand new out of the box.
View solution in original post