How will you delete duplicating rows from a base table?

How will you delete duplicating rows from a base table? 

delete from table_name where rowid not in (select max(rowid) from table group by duplicate_values_field_name); or delete duplicate_values_field_name dv from table_name ta where rowid <(select min(rowid) from table_name tb where ta.dv=tb.dv);

What is syntax for dropping a procedure and a function .Are these operations possible?
Drop Procedure procedure_name
Drop Function function_name