Selectively ignoring tuples from a table
You can accomplish this with a window function like the ROW_NUMBER() function inside of a subquery or CTE like so:
SELECT id, colA, colB, revFlag
FROM
(
    SELECT id, colA, colB, revFlag, 
        ROW_NUMBER() OVER 
        (
            PARTITION BY colA 
            ORDER BY CASE WHEN revFlag = 'REVISED' THEN 1 ELSE 0 END DESC, id DESC
        ) AS SortOrder -- Generates a unique ID for each row of the same value of colA sorted by revFlag = 'REVISED' first then by id descending
    FROM myTable
) myTableSorted
WHERE SortOrder = 1

As per my comment, the SortOrder field is generated by partitioning on colA and within that partition generating a unique incremental id that is sorted with the revFlag = 'REVISED' having priority first, and then by the myTable.id column descending (to get the latest row per colA).