A default template has accidentally been made and continues to open on start up of Excel. How can I delete a default template in 2010?
Unlike Word, Excel doesn't have a Normal template.
What you can look for however is Book.xlt/.xltx/.xltm and Sheet.xlt/.xltx/.xltm under
Book.xlt is used as the basis for new workbooks, and similarly Sheet.xlt is used as the basis for new worksheets added to existing workbooks.
There are multiple places to check. See the list under the third option on this page:
It says Excel 2003 but apparently this is still applicable.