Jamieson, Fausset and Brown on Colossians 2:20

20. Wherefore--The oldest manuscripts omit "Wherefore."

if ye be dead--Greek, "if ye died (so as to be freed) from," &c. (compare Ro 6:2; 7:2, 3; Ga 2:19).

rudiments of the world--(Col 2:8). Carnal, outward, worldly, legal ordinances.

as though living--as though you were not dead to the world like your crucified Lord, into whose death ye were buried (Ga 6:14; 1Pe 4:1, 2).

are ye subject to ordinances--By do ye submit to be made subject to ordinances? Referring to Col 2:14: you are again being made subject to "ordinances," the "handwriting" of which had been "blotted out" (Col 2:14).