Those verses are difficult to understand. Jesus is talking about "The Law and The Prophets." These are names the Jews had for sections of their scripture. Meaning the actual composed work of sacred texts the Jews had at the time. He had not come to change them. He did come to fulfill them, meaning the prophecies contained therein.
Almost the entire Judaic law is in prophetic reference to the coming of their Messiah. Christ, as their Messiah, fulfilled these prophecies, and by so doing, requires their practice no longer. Don't be confused, this doesn't mean He doesn't require the practice of all things He had revealed, only those of the Mosaic law.