Why can't I drop certain players?
UNDROPPABLE PLAYERS
The Undroppable list comprises players who cannot be dropped to waivers at any time during the season. ESPN introduced this feature to prevent collusion (In these cases, owners would be able to drop star players, allowing those first on the waiver wire to pick them up). League creators of ESPN Custom and LM Leagues can choose if they want to allow owners to be capable of dropping all players or be prevented from dropping designated players by going to the LM Tools tab and clicking on Edit League Settings, then clicking "Edit" next to Player Rules and then selecting "No" next to "Observe ESPN's Undroppable Player List.

View your league settings page to see how your league is configured. In Standard Leagues the list is enforced at all times.

View the players listed as undroppable.