Based on your answer to my comment, You have a table with single column and you want to de-duplicate that table, is that the correct understanding?
If yes, check the following code taken from source below. That should do the trick
LEFT OUTER JOIN (
SELECT MIN(RowId) as RowId, colName
GROUP BY colName
) as KeepRows ON
MyTable.RowId = KeepRows.RowId
KeepRows.RowId IS NULL
Code from : http://stackoverflow.com/questions/18932/how-can-i-remove-duplicate-rows
Hope that helps.