You can delete the unused bank accounts, as it won't affect your financial records, guy.
First, may I ask if other users are accessing your QuickBooks account? If so, they may have connected the two additional unused bank accounts, which is why these accounts are appearing in your QuickBooks.
Since you are only actively using one bank account, deleting the other two accounts will not affect your overall books. However, please note that any existing transactions associated with those deleted accounts will also be removed.
You can also categorize your downloaded bank transactions so QuickBooks can put your transactions on the correct line of your Schedule C.
Should you have additional questions or concerns, we’re always ready to assist you.