The hair has started to slip! Using the same method as "fleshing", you can easily scrape off the hair AND the grain layer in this particular piece. If you're planning to bark tan the skin, leave the grain on. Of course, you can bark tan a grain off skin, but it'll be less water resistant. The grain helps the leather to repel water naturally.
For making buck skin, the grain is taken off. Once soaked for 3 days, the grain and hair just slides off with a blunt edge. No nassssty chemicals like Ca(OH)2 is needed, really, but if you like to have things easy, sure, lime it. Just make sure you rinse and neutralised all the lime outta the hide afterwards.