How to delete duplicate records in Oracle Table

I would consider that the duplicated columns appear one after the other in the table

If yes; below SQL Query will take you through. You may add or remove additional column conditions in your where clause to satisfy the specific scenario

 

DELETE TABLE A WHERE ROWID >(
select min(rowid) from TABLE b
where a.<table.column1>=b.<table.column1>
and a.<table.column2>=b.<table.column2>)

But if your duplicated columns do not appear in the continuous order; I would recommended you create a temporary table that stores the data in the intended ordered format and the proceed with the above operation. You can then later replace the rows of your original table with rows from the Temporary Table

CREATE TABLE TABLE_TEMP AS SELECT * FROM TABLE ORDER BY <table.column1>