That's correct. Demonetization is the process of revoking the legal tender status of a particular currency unit, rendering it no longer acceptable as a medium of exchange for transactions. When a currency is demonetized, it typically means that the government or central authority has declared that the currency notes or coins of a certain denomination or series will no longer be valid for financial transactions. This can be done for various reasons, such as to combat counterfeiting, control inflation, or promote the use of a new currency.
People holding such currency units are often provided with a window of time during which they can exchange the old currency for a valid one or deposit it in a bank. After the demonetization process is complete, the old currency becomes obsolete for day-to-day transactions.