It doesn't matter whether I am trying to use Hulu, Amazon, Netflix, etc. SlingTV keeps popping up no matter what I have tried. I cancelled SlingTV about a year ago and have been subscribing to Hulu ever since. These last few days Sling has taken over and keeps asking to renew. I can't watch anything else now with these interruptions that won't go away.
Do you have a Sling button on your remote? Is it stuck? Do you have another Roku remote you can use or can you use the Roku app on a phone/tablet to see if the problem is with the remote?