,COUNT(*) as '# records'
FROM [LZ].[dbo].[lz_src_address1] a
where a.sch_type = '23'
group by a.dr_id, a.sch_type
having COUNT(*) > 1
You only include the fields that you need to determine if its a duplicate and put them in the GROUP BY clausing. the HAVING clause tells you if there is more than 1 record.
There are several ways to delete duplicates. They way you choose will depend on if you have a unique key for each row. If so, you can delete them with a single statement. If not, you may need to use a cursor and/or temp tables.