League commissioner

As the person who created the league can I drop a player in a theme league which shouldn’t be on this players team? Is there anything I can do about it.

Yes, you can drop him, even if it puts the offending manager below the roster requirement of 24.
If you do it BEFORE waivers, you can only drop the player.
If you do it AFTER waivers, you can drop the player and add an eligible player as well, if that's what is needed.

Yes, you can drop him, even if it puts the offending manager below the roster requirement of 24.
If you do it BEFORE waivers, you can only drop the player.
If you do it AFTER waivers, you can drop the player and add an eligible player as well, if that's what is needed.

It wont allow me to when I go to the roster. At least not in the same manner I would typically go to drop a player on my team. When I go to the “your team” > “Roster” page. Should I go somewhere else to do this? Keep in mind it was a public league I created and not a private league. I wonder if that is the reason.

Yeah, I don't think public leagues can have a Commissioner.