If you want to unfollow a player on the app, simply click on the player section at the top right:

Click on Manage:

Select the player you want to "unfollow".

Click on Unfollow.

IF the Unfollow is not there and it says Follow, it means you are not currently following the player.

Why is he there? You're asking yourself.

B. He is a recently searched player 

C. He is a favorite player. 

In that case you can choose to uncheck the Favorite Star or Put in Trash can if he's a recently searched player.