Open the Netflix app on your Roku
Select a profile if prompted
Press Left on the Roku remote to open the Netflix menu
Scroll down and select Get Help
Select Sign out
Confirm by selecting Yes
If you do not see Get Help, press the following on your remote: Up, Up, Down, Down, Left, Right, Left, Right, Up, Up, Up, Up
Select Sign out from the hidden menu
Confirm the sign-out
If needed, remove Netflix from the Roku home screen and add it again to fully reset the app