Instagram’s Unlink Account feature is deceiving, at least when it comes to Facebook. Since Instagram is a Facebook company your two accounts will forever be connected.
That’s because the wealth of data that Facebook collects through its multiple services is more than enough to properly identify users’ various accounts and link them to one another. Even in cases where a different name, email address, or device was used to create each account—be it a throwaway WhatsApp profile, stalker Instagram account, or joke Facebook profile—Facebook often is able to suss out who is actually behind the account and whether they have accounts on other Facebook-owned apps.
Check It Out: Instagram’s “Unlink Account” Feature is Deceiving