Removal spells are cards that can destroy or otherwise remove a creature from the opponent's field
Believe it or not, we actually have both of those things in Standard right now
One of the leaders is Caradora, Heart of Alacria, and one of the team's Vehicles is Lagorin, Soul of Alacria (which is actually a mount, meaning a creature with Saddle Up) The Champions of Amonkhet - White and Black color identity
(It's also not an enchantment they can kill to get their dork back, by the way) But by discarding it for an effect, you net the effect as well as a powerful madness theft of something at instant speed that can change the tables very quickly
(To mill a card, put the top card of your library into your graveyard.) You put a +1/+1 counter on Ravenous Gigamole if you don't put a creature card into your hand with its ability, even if there wasn't a creature card among the milled cards
However, if it phases out with that triggered ability on the stack, it won't be exiled, and the delayed triggered ability won't trigger again during future end steps.