In case you're still tryin'.....once you go to roster and click one of your 6 select player icons, the player list opens up...
to select a player, click the little green bubble next to the player's photo---done
you can "x" them out right on that page or when you go back to the main page should you desire to change before the event starts...
and Zalatoris is listed in the alphabetical pool at the very end---make sure there is nothing on your computer page obscuring the bottom entries---like the dreaded "accept cookies' bullshit