You mean during a VBA program, right? Because I don't know whether you can do that when you're closing the workbook manually, and anyway this is the VBA-programming forum.
First, get used to https://learn.microsoft.com/en-us/office/vba/api/overview/, which is an excellent source of documentation on all things Office-VBA. For information on the Close method, for example, click on "Excel" at the left, then select "Object model". Go down the list looking for the object that the Close method belongs to (which is the Workbook). Click on "Workbook object", then "Methods", then "Close". That page will tell you that to close the workbook without saving changes, use False as the first argument.
