Remove element from array, using slice

I am trying to remove a element from my array using slice, but i can't get it to work, look at this piece of code.

    console.log(this.activeEffects); // Prints my array
    console.log(this.activeEffects.slice(0,1)); // Remove from index 0, and remove one.
    console.log(this.activeEffects); // Prints array again, this time my element should be gone

Result of this is.

So what is get from this is, at first the array is whole, as it should be. Then its prints what is sliced of the array. Finally the third should be empty? or?