From within that channel app see if you can find a place to Sign Out / Log Off or similar wording. This is typically under Account / Settings / Options or similar location.
You should then be able to sign back in with the correct provider information.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X