Hi, vivianaec!
I appreciate your time and patience in utilizing QuickBooks.
Yes, it is the main expense. Expense is the cost of an asset used by a company and this is the main category while the subcategory doesn't map to unique accounts in the chart of accounts.
You can check for this article that will help you guide you on how to add, edit, or delete accounts in QuickBooks Desktop.
Feel free to get back on this post, I'm always here to help.