The biggest question I have is why are you tearing off the siding to begin with?

If you are thinking you want to expose the cedar shingles beneath the vinyl, you will probably be disappointed with what you find and understand why the shakes were covered in vinyl in the first place.

You will also probably find them filled with nail holes and likley split beyond use from all the fasteners which held the vinyl, and you could be in for a time if you plan to repaint or restain what you find.

If your existing shingles are not useable, replacing cedar shingles is a very expensive proposition.

Without knowing your intent by removing the vinyl, it’s hard to advise otherwise.

But if it is to expose the old cedar shingles, you might want to reconsider and have a professional remove only a small portion of the vinyl so you can observe their condition before going further, and the pro reinstall the siding if what you find is not positive.