Try:
SELECT SUBSTRING(areacode, 1, 1) + SUBSTRING(areacode, 3, 1000) AS Areacode, areaname FROM MyTable
"I want to update that column .not only select"
So tell us exactly what you want!
It's a trivial mod anyway:
UPDATE MyTable SET areacode = SUBSTRING(areacode, 1, 1) + SUBSTRING(areacode, 3, 1000)
But backup first incase you make a mistake: always backup before you run an UPDATE without a WHERE clause!