Deleting a column

You can delete a column using the DROP COLUMN clause of the ALTER TABLE statement.

Dropping a column deletes that column from the table definition. If CASCADE is specified, any views, indexes, and constraints dependent on that column will also be dropped. If RESTRICT is specified, and any views, indexes, or constraints are dependent on the column, the column will not be dropped and SQLCODE of -196 will be issued. 

ALTER TABLE DEPT
  DROP COLUMN NUMDEPT
Parent topic: Changing a table definition
Related reference:
ALTER TABLE