This is a very easy way to clean a Keurig coffee maker with vinegar.
Pour vinegar into the Keurig coffee machine and run a brew cycle (with no k-cup) until the vinegar comes out clean.
Run a few brew cycles of just water through the machine to remove the vinegar.
Clean the inside with a sponge or cloth (with a little bit of soap) and little cleaning brushes to get in between the little crevices.
Use a cloth or sponge to clean the outside of the machine with warm soapy water or vinegar.
Run more brew cycles with water until there is no vinegar taste (4 or 5 times).