To link your IG and FB accounts and use posts openly from Instagram to Facebook:
Access your profile and select .
Click Settings.
Click Account, next select Linked Accounts.
Click Facebook and input your login info.
By default, your IG account will connect to your personal FB profile. To connect to a Page alternatively, select Share to and choose the Page you would like to manage. There are numerous reasons to do this. Many times, people convert a personal account to a Facebook business account. Therefore, you need to know how to delete your Facebook account or connect it as explained here.
How to Unlink Facebook and Instagram
Open up IG on iOS or Android, select settings icon, located in the upper right under profile. From here, scroll below to Settings, and find Linked Accounts. Now, you will see Facebook is highlighted blue. Also, make sure there is a checkmark. Click the check-mark, then click “Unlink Facebook” button.