If i remember this correctly, to delete a linked instagram account.

How to delete instagram account connected to main account. Tap/click on next to username and select log out. Scroll down and click or tap on. Tap/click on “edit profile” next to your username.

Choose “profile” from the list of options. Log into your account and click. Tap account, then tap delete account at the bottom.

Tap on the button with three lines, and then tap on. If you’d like to delete a different account: Tap in the top right, then tap settings.

Log in to your instagram account and navigate over to your profile page. Tap the account profile picture to launch the profile menu. Log in to instagram on a browser.

Tap in the top right, then tap settings. Scroll down and click “ temporarily. Once you’re signed in, select a reason you want to delete your account.

I had the same problem and was panicking cause maybe i couldn't delete it but i eventually found out how to! In the list that opens, tap accounts. Tap next to the account you want to remove.