Converting .xlsm files to .xlsx format.
Using Microsoft Excel, you can easily export your .xlsm files to the default .xlsx format (MS Excel Macro-Enabled Spreadsheet to MS Excel Spreadsheet).
Converting .xlsm to .xlsx in that way will disable some, or all macros in the resulting default format.
Simply use the 'File - Save as...' function in MS Excel. This might also be possible in other programs supporting Excel file types.