delete duplicate rows

1WITH cte AS (
2    SELECT 
3        contact_id, 
4        first_name, 
5        last_name, 
6        email, 
7        ROW_NUMBER() OVER (
8            PARTITION BY 
9                first_name, 
10                last_name, 
11                email
12            ORDER BY 
13                first_name, 
14                last_name, 
15                email
16        ) row_num
17     FROM 
18        sales.contacts
19)
20DELETE FROM cte
21WHERE row_num > 1;
22

1WITH CTE AS(
2   SELECT [col1], [col2], [col3], [col4], [col5], [col6], [col7],
3       RN = ROW_NUMBER()OVER(PARTITION BY col1 ORDER BY col1)
4   FROM dbo.Table1
5)
6DELETE FROM CTE WHERE RN > 1
7