If you can open the case of the computer, it's inner parts are upgradable. But if you cannot put back the inner parts in the original case anymore, then it might not be such an good idea to upgrade. And this is a choice only the owner of the device should make. Besides the above, getting the upgraded parts to work correctly with the original hardware could be an Herculan effort. Desktops usually contain parts that are easily interchangeable. Laptops are much more problematic in that regard.
From a very brief search on Google I understand that Lenovo Yoga models are difficult to repair. Still, upgrading a hard disk should in theory not give you much problems, unless it is soldered or glued to the mainboard. In those cases all bets are off. It could still be relatively easy if you have the expertise and equipment at hand, but there is a much higher chance you end up with a pretty expensive doorstop.
Repairability/upgradability from any model of computer I intend to purchase is the first thing I look for. Especially nowadays, where more and more manufacturers apply "planned obsolescence" into all of their products.