If you have the black box with the 10/10 score there is no patch on the disk.
If you have skyrim installed with the 1.5 patch (and obviously you have no internet connection), then if you delete the game you will lose that patch.
So either way don't delete your game, or if you install it again, (and you have internet connection after all) this game will be updaded to patch 1.9.
Either way you don't update the game on-line, so you don't have to worry about downloading the 1.9 patch - or you update it and the get the 1.9 update.
So, you play vanilla skyrim like the first day release (11.11.2011) or you play it with the latest patch.
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Beside that i wouldn't suggest you to play un-patched because if your save files relies on the 1.5 update you will have problems with the game at some point...!!!!
( but if you start with a new character, it's up to you downloading or not the latest patch !!! )