Substring removing in Swift

var dataString = "Substring removing"

var start = dataString.startIndex.advancedBy(9)
var end = dataString.endIndex
dataString.removeRange(start..<end)
//dataString is "Substring"

start = dataString.startIndex
end = dataString.startIndex.advancedBy(2)
dataString.removeRange(start...end)
//dataString is "string"