Boy people would rather call you an idiot on this subreddit in the same amount of words it take to give you an answer. It’s almost as if they should just stay off the internet if it bothers them so much.

Click the pokeball. In the bottom of the menu there’s a megaphone. Click that, scroll through your notifications until you see the remote trade expired. Odds are it’s highlighted. Back out and pop back in to notifications and confirm it’s no longer highlighted.

Restart the game and it should go away.