Delete Chart of Account Items

I am trying to delete items from the Chart of Accounts, but I get the message that the account in in use in: FTC account in setup or UCP account in setup. What does this mean

The first error, FTC, means that the account you are trying to delete is set as the Fuel Tax Credit account in your BAS setup. Change this account and you will be able to delete the account. 

The second error, UCP, means that the account is in use as the Unapplied Payments Account in the Debtors Setup. As above change this to a different account and you will be able to delete the account.