Hi there, @Chelsea Wambua. I'm here to provide some info and steps to help you import your Chart of Accounts (COA).
May I know the error message you're getting? You're unable to import duplicate accounts in QuickBooks Online (QBO). Make sure that the COA names you're trying to import aren't identical to the existing ones.
If you wish to import a new set of accounts, you can inactivate the existing ones. There are a few things you need to know before doing the process. Refer to this article: Make an account inactive.
Next, follow these steps:
Go to the Gear icon and select Chart of accounts.
Select the accounts you want to inactivate.
Select the Action dropdown and select Make inactive.