My CC has a CORP umbrella account linked to it. In QBO onboarding I was told its OK to delete the CORP act linked, however now my starting CC balance is negative. Help?

You've come to the right place, @usercontact10.

Have you entered an incorrect opening balance? Or do you have transactions that are older than the opening balance? If so, this might be the reason for having a negative balance in your Credit Card account. To resolve this, let's start by reviewing your account's opening balance entry in the Chart of Accounts. Refer to these steps:

1. Go to the Accounting menu, then click Chart of Accounts.
2. Look for the Credit card account on the list. 
3. Tap View register.
4. Search for the opening balance entry. It should have Opening Balance Equity in the Account column.
5. Make a note of the date and balance. 

If you're already tracking transactions in the account but forgot to enter an opening balance. You can do it manually.

Once done, compare the balance on your bank records to what you entered as the opening balance in QuickBooks. If the amount doesn't match your statement, edit it. Here's how:

1. Go back to your bank register.
2. Click the opening balance entry to expand the view.
3. From the Deposit column, update the balance so it matches your bank records.
4. Tap Save.
5. Select Yes to confirm.

When finished, pull up the Balance Sheet and Trial Balance reports. If you get the same result, proceed to Step 2 of this article: Fix beginning balance issues in QuickBooks Online. 

Also, when creating transactions from the credit cards you have to choose the appropriate Expense accounts or Accounts Payable if there's a bill.

I've also added, this great source that you can read to help you categorize your downloaded transactions: Match and categorize your downloaded bank transactions.

Please post here again if you need further assistance fixing your credit card balance in QuickBooks. I'm always here to help. Have a good one.