This app was mentioned in 10 comments, with an average of 1.60 upvotes
Firstly, no, it's too late to use a tool. But are you on iOS or Android? If Android, I'd recommend checking this out: https://play.google.com/store/apps/details?id=com.andrewtretiakov.followers_assistant. You can use this to keep track of the people you follow going forward.
I use Followers Assistant and it's great. You can batch un-follow with it (up to 200 at a time, I believe). As others have mentioned, IG will slow you down and block you from un-following or following for about an hour if you do it too much. Un-following 50-100 an hour, you should be safe (but I wouldn't suggest more than 700 in a 24 hour period).
Hmm, you could give Followers Assistant a go. It's inexpensive and I think it works on multiple accounts. It's for android.
https://play.google.com/store/apps/details?id=com.andrewtretiakov.followers_assistant
I didn't use that app, so I don't know all it does, but I've been on something called Followers Assistant and like it. https://play.google.com/store/apps/details?id=com.andrewtretiakov.followers_assistant
Try this one Works similarly
I use Followers Assistant for this very reason. Its free and easy to use. https://play.google.com/store/apps/details?id=com.andrewtretiakov.followers_assistant&hl=en
Try Followers Assistant -> Play Store
I use Followers Assistant on Android, works great to see who follows/unfollows.
I use Followers Assistant -- it works very well.