SQL Delete duplicate rows based on column

To remove duplicate rows, use a CTE and partition using the data you want to check for duplicates to assign a row_number against. Then remove any where the row_number > 1 (removing multiple duplicates)

WITH CTE AS
(SELECT ROW_NUMBER() OVER
(PARTITION BY computername ORDER BY ( SELECT 0)) RN
FROM temp_devicerefresh)
DELETE FROM CTE WHERE RN > 1