Place the bud horizontally into a rubber-guarded vice or a pair of blunt pliers.

Apply steady, even pressure to either side of the bud along the main housing seam (the seam between the two arrows). The pressure should break the seal.

Only apply enough pressure to create a small gap between the two halves of the bud. If you use pliers, put a cloth between the pliers and the buds to prevent the teeth from digging into the soft plastic.