Apps and services can connect with your Instagram account if you allow them to. Instagram isn’t used as an online ID like Google accounts and Facebook profiles however it can still be used to sign into apps and services that support it. There aren’t very many of them but they are there nonetheless. If you want to remove authorized apps from Instagram, you can do so from Instagram’s web interface.
You can’t remove authorized apps from any of the Instagram apps, odd as that is. Visit Instagram in your desktop browser. Go to your profile and click the cog wheel button at the top next to the Edit Profile button.
A pop-up will open with an ‘Authorized Apps’ option. Click it.
On the next screen, you will see a complete list of all apps and services that you’ve allowed to connect to your account. Under each app/service is a Revoke button. Click it, confirm that you want to revoke the app/service’s access, and it will be removed.
It goes without saying that if you remove an app from your Instagram account, the app or service will no longer be able to function. For services like IFTTT, removing it will make it so that the service can no longer post to Instagram per a recipe, nor will it be able to post to it.
You can always add an app or service back if you remove one by mistake. To do so, visit the app or service and tap the Instagram sign-in option. Allow the app/service to connect to your account.
Removing an app will not delete the data that the app has stored. If you suspect an app is malicious and it is selling your information or misusing it in some other way, removing its access is a good idea however, that does not guarantee the app or service will also delete the information it already has. If you suspect an app has been maliciously using your information, you can check to see if there’s any way to delete your account on the app itself.
The odd thing is, you cannot remove authorized apps from the Instagram apps. You need to go to the web version. It’s odd because Instagram was, and continues to be, a smartphone app. Its web interface does not support its core function i.e., uploading photos yet that’s where you have to go to remove an app that has access to your account. The revoke apps options should be present on the apps.