Delete projects

Open the excel file containing the macros. Press Alt+F11. It will open up the code window. On the left hand side, you will see Microsoft Excel Objects and below that Modules, like Module 1, Module 2, etc. You can either right click and remove each module or just clear its contents manually. Select all code and delete.

Then double click on each sheet in the same code window on the left hand side. If there is any code attached to each sheet, it will appear on the right hand side. Select the code and delete.

Then save your file as .xlsx.

When you do a Save As of your file, select Microsoft Excel Workbook from the dropdown below the filename.