SQL & PL/SQL

Hello Every Body.
i want to drop/delete the column of the table,so how can i do that?
For example. i have table

CREATE TABLE CUSTOMER
(
Customer_ID NUMBER,
Customer_Name VARCHAR2(10),
Street VARCHAR2(10),
City VARCHAR2(10),
State VARCHAR2(10),
Postal_Code NUMBER,
PRIMARY KEY (Customer_ID)
);

now i want to Delete the column Postal_Code .
So what should i do??

Regards