password protected excel in office 365

amitmahapatra 

The only option you have is to open the file in another Office package (no Excel for Web, best Excel 2007 to 2016) and unlock the file, see the instractions down unter please, if you need  to open a .xlsm file you need a VBA code.

If this is necessary, please contact me again.
You can do this as long as it is your workbook.
Attention: You may only use the following instructions for your own files. Otherwise you could be liable to prosecution.

Unprotect Excel sheet without password using 7-ZIP (free software)
Für diese Anleitung benötigen Sie das Programm 7-Zip, herunterladen können Sie dies in Internet: https://www.7-zip.org/download.html

Folgen Sie dann unserer Schritt-für-Schritt-Anleitung oder schauen Sie sich die Kurzanleitung an.
Note: This way only works for Excel file in .xlsx format.
Hence, if your Excel workbook is in .xls format, just open it and then save it as .xlsx format.

Step 1: Change the Excel file name extension from .xlsx to .zip. Just click on Yes to make sure when prompted.

Step 2: Open the ZIP archive as 7-ZIP. Open the folder xl->worksheets and you can see threesheet.xml files. Select the sheet1.xml file. Right click on it and select Edit. Choose to open it withNotepad.

Step 3: Delete the tag beginning with sheetProtection. Then save and close the sheet1.xml file.

Step 4: Update the modified sheet1.xml file in the ZIP archive when prompted. Then close the ZIP archive.

Step 5: Change the ZIP fie name extension back to .xlsx. At this point, the Excel sheet has been unprotected. Open it and you can edit the sheet without password.