Re-use yarn

I wasn’t happy with my last two projects (sweaters) and took them down. Can I just start a new project with the yarn, or do I need to do something to it first? One yarn is Rowan Purelife chunky , the other is “Possum Supreme” (!) which is merino and possum (yes, possum).

You should just be able to knit with the yarn. Even if it’s kinked a little, if you’ve wound it into loose balls that should straighten it out enough.