I have some insight on this cash sales question that I'm sure you'll find helpful. As you've noticed, the default Cash Sales Account for QuickBooks Online is called Undeposited Funds. While you can rename it to whatever you'd like, it can't be deleted as it is necessary for any income transaction that doesn't have a Bank account specified.
Undeposited Funds is also used as a holding account of sorts for the purpose of creating batch deposits where the money received by the bank may represent multiple combined customer payments. These resources can offer additional information on the account for your benefit:
To best determine which use of these accounts best suits your unique business, I recommend reaching out to an accounting professional. Intuit's Find-An-Accountant service can put you in touch with certified experts who will be more than willing to take a closer look at your situation.
Please know you can always reach me should there be anything else you need, I'm always up to talk QuickBooks. Thanks for reaching out, wishing you and your business great success in all that you do.