instagram_web_unfollow.js

const randInt = (min, max) => Math.floor(Math.random() * (max - min + 1) + min) // min and max included
const sleep = ms => new Promise(resolve => setTimeout(resolve, ms))

const followersElement = getFollowersElementWithUsername(getUsername())
followersElement.click()

function getUsername () {
  const pageTitleElement = document.getElementsByTagName('h2')[0]
  if (!pageTitleElement) throw new Error('No title to get username from')
  return pageTitleElement.innerHTML
}

function getFollowersElementWithUsername (username) {
  const followersElement = document.querySelectorAll('a[href="/' + username + '/following/"]')[0]
  if (!followersElement) throw new Error('No followers element was found')
  return followersElement
}

const friends = new Set(['user1', 'user2'])
const unfollows = {}
let tries = 0
let globalCount = 0
const hasMoreToLoad = ul => ul.childElementCount !== globalCount || ul.children[ul.childElementCount - 1].firstChild.getAttribute('data-visualcompletion') === 'loading-state'
const populateUnfollowsPool = () => {
  const ul = document.querySelectorAll('ul')[1].firstChild
  const lis = [...ul.querySelectorAll('li')]
    .map(li => ({ button: li.querySelector('button'), name: (li.querySelector('a') || { href: '' }).href.split('/').slice(-2)[0] }))
    .filter(({ button, name }) => button && button.textContent === 'Following' && name && !friends.has(name) && !unfollows[name])
  lis.forEach(({ button, name }) => (unfollows[name] = { button, name }))
  globalCount = ul.childElementCount
  ul.children[globalCount - 1].scrollIntoView(true)
  console.log('elements', globalCount, 'unfollows', Object.keys(unfollows).length, 'tries', tries)
  setTimeout(() => hasMoreToLoad(ul) || tries++ < 3 ? populateUnfollowsPool() : finishedCollection(), randInt(848, 2004))
}
setTimeout(populateUnfollowsPool, 3000)

async function finishedCollection () {
  console.log('!!! Collection Finished')
  const toUnfollow = Object.values(unfollows)
  const total = toUnfollow.length
  for (let i = 0; i < total; i++) {
    const { button, name } = toUnfollow[i]
    button.scrollIntoView(true)
    button.click()
    await sleep(randInt(50, 200))
    const unfollow = [...document.querySelectorAll('button')].find(button => button.textContent === 'Unfollow')
    unfollow && unfollow.click()
    console.log('Unfollowed ', name, (i / total * 100).toFixed(2), '%')
    await sleep(i % 8 ? randInt(120, 800) : randInt(1, 10) * 60 * 1000)
  }
}

Adaption here: https://gist.github.com/mikeknapp/788cb26da096161ef3fff1015d947405