Understanding the recreation of index in Table partitioning
Dropping the index is not required, and is likely a coding oversight in the wizard output.  It appears you've not just blindly ran the generated code; this is a Good Thing™, and is why I much prefer to write my own T-SQL statements by hand.

The procedure for modifying a clustered primary key to a non-clustered primary key, then adding a clustered index to a separate column is exactly as you've described:


DROP the primary key constraint.
ADD a new primary key constraint with the NONCLUSTERED keyword.
CREATE a clustered index on the desired column.


The DROP INDEX statement is certainly not required.