Jungkook has deactivated his Instagram account, according to his Weverse post. His reasoning for it: he just wasn't using it. Simple.
Check out his Weverse posts below:
JK: I left Instagram. It's not a hack. :) I just erased it because I didn't do it. Don't worry!!!
JK: Hehehehehe I never used it, what could I do!? I just want to use Weverse live every once in a while.
JK: I deleted the app right away. I don't think I'll have to do it in the future. I'll let you know in advance! Hahaha