It was really interesting taking apart sweaters, particularly from early on in my knitting career when I had no idea what I was doing. Tying in the ends? That's not how we do things any more. Then again, splicing together yarn results in some enormous hanks of yarn.... Anyway.
Step one: Unweave your ends. Curse your younger self who inexplicably tied the ends to the knitting. Or who split through single ply yarn when weaving.
Step two: Unseam your seams.
Step three: Frog! Wind into a ball. This will create a lot of fiber dust that gets in your nose and makes you sneeze.
Step four: Skein. I used my handy dandy niddy noddy and skeined up all the yarn. This was surprisingly tiring for my arm and shoulder. I tied off the hanks using scraps of sock yarn.

Step five: Soak the skeins.

With a little wool wash.

In a rubbermaid tub. Black and red went first.

Then the blue. It looked like Smurf ramen, frankly.
Step six: Wring out the skeins.Get out that water!

Spot the cat? Wringing out the skeins took a lot of time. Like, a lot of time.

Cat's easier to find on this one.
Step seven: Hang skeins to dry.

Batch #1.

All the yarn. Be annoyed that cat destroyed collapsing fabric box...
Step eight: Wait for skeins to dry. Wait some more. Give it another day.
Step nine: Call it dry enough and retwist all the skeins. Realize that you don't have space to store all this yarn...

Seriously, this is a lot of yarn. There's also a few un-washed balls of reclaimed yarn that I may not bother with processing. We'll see.
The process worked pretty well. Some of the yarn still has a little wave to it, some looks brand new. The red yarn is nicer than it ever has been. It was a lot of work, but I'm glad I did it. Now I need to knit some worsted/aran/bulky weight sweaters to decrease this reclaimed stash!