How To Drop an Index?

If you don't need an existing index any more, you should delete it with the DROP INDEX
statement. Here is an example SQL script:
CREATE TABLE student (id NUMBER(5) PRIMARY KEY,
first_name VARCHAR(80) NOT NULL,
last_name VARCHAR(80) NOT NULL,
birth_date DATE NOT NULL,
social_number VARCHAR(80) UNIQUE NOT NULL);
Table created.
CREATE INDEX student_birth_date ON student(birth_date);
Index created.
SELECT index_name, table_name, uniqueness
FROM USER_INDEXES WHERE table_name = 'STUDENT';
INDEX_NAME TABLE_NAME UNIQUENES
----------------------- --------------------- ---------
SYS_C004129 STUDENT UNIQUE
SYS_C004130 STUDENT UNIQUE
STUDENT_BIRTH_DATE STUDENT NONUNIQUE
DROP INDEX STUDENT_BIRTH_DATE;
Index dropped.