Open Facebook app
Tap Menu (three lines)
Go to Settings & privacy
Tap Settings
Tap Accounts Center
Tap “See more” (if shown)
Tap Profile settings
Tap Linked experiences
Find Instagram
Tap Remove
Confirm by selecting Remove account
Open Instagram app
Go to Profile
Tap Menu (three lines)
Tap Settings and privacy
Tap Accounts Center
Tap “Personal details” or “Connected experiences” (wording may vary)
Tap Connected accounts
Select Facebook
Tap Remove
Confirm removal
If prompted, log out and log back in to both apps