When working with Oracle database, you may encounter the error : ORA-02429: cannot drop index used for enforcement of unique/primary key. This tutorial will show you how to solve this problem.
As stated in the documentation, Oracle Database enforces a UNIQUE key or PRIMARY KEY integrity constraint on a table by creating a unique index on the unique key or primary key. This index is automatically created by the database when the constraint is enabled. The ORA-02429 error happens when you attempt to drop the index with first dropping the constraint (primary key)
You need to drop unique or primary key constraint.
ALTER TABLE TABLE_NAME DROP CONSTRAINT CONSTRAINT_NAME
ALTER TABLE USER_NAME DROP CONSTRAINT CONSTRAINT_NAME