In the Excel file press ALT + F11 to open the Visual Basic Editor. In the left hand pane can you see anything called Modules (you may need to click on the +s to open up the view. If you see Modules double click it then on click on each module in turn and File > Remove module.
If that doesn't work right click each tab select View Code and delete anything there. Right click the Excel logo at the left of the title bar and do the same.
Failing that, add a new blank sheet. Select all of the other sheets (click the first one then hold down CTRL and click the others) Edit > Move or copy sheets, in To book select (new book). Click OK - you will now be in the new workbook. Save it.