Sharing tab on activity app isn't showing

I'm trying to remove a friend from my shared activity, and every post I've come across only tells me that I need to click the "sharing" tab in my activity app and then remove friend. My issue is that in my activity app, I do not see the "sharing" tab. I only see "my watch", "face gallery", "app store", and the magnifying glass to "search app store". I have a series 4 watch running 5.3.1 and an iPhone XS Max running 12.4.1. Can anyone help me figure out how to get to my sharing in the app???