There is a reset button on the Roku device.
First, log in to your account https://my.roku.com/ and Unlink the device(s).
Next, plug in the device and hold down the reset button for at least 30 seconds. That means exactly that. Not about 30 seconds. Not 30 but accidentally let the button go once or twice. Hold it down continuously for at least 30 seconds. Then, it's wiped (Reset does that) and stuff won't come back (the Unlink makes sure of that).
DBDukes
Roku Community Streaming Expert
Note: I am not a Roku employee.
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