Stick your national focus on Connaught then you can settlement polict the whole island. If that's too intense just stick a settlement policy on Connaught and wait for it to spread naturally. Once they become english, the Irish will lose their cores within 50 years, instantly if you promote cultural unity.
That's the best way to remove the Irish from the game. English culture will not spread in Ireland unless at least one of them has been converted to English already. This is, however, not a very good idea if you're a blobbing colonial Britain: The loss of magistrates and colonists from settlement policies is not worth the fraction of increased income this would bring you. You could make the case for it if you were holding only the UK and perhaps a dosen or so mainland provinces, but otherwise, no.