Source : Webster's Revised Unabridged Dictionary (1913)

Demonetize \De*mon"e*tize\ (?; see {Monetary}), v. t.
   To deprive of current value; to withdraw from use, as money.

         They [gold mohurs] have been completely demonetized by
         the [East India] Company.                --R. Cobden.

Source : WordNet®

demonetize
     v : deprive of value for payment; "demonetize a coin" [syn: {demonetise}]