Hi @GilWal-93
If you have no device swaps left this calendar month by going to My Account > Devices on here where you will need to remove the Xbox off the list, then after it is removed starting watching some nowtv stuff on your Xbox again to automatically re add the Xbox back onto your account device list.
Then jump over to live chat and ask them to reset all your devices, which should then clear the message from your Xbox.
Link to live chat below.
https://help.nowtv.com/contact-us/managing-my-devices