I recently came upon a Python package that simplifies this process.
It doesn't require Excel to run, and it's also cross-platform because it's written in Python.
Microsoft Office password-protected (encrypted) documents, including the older XLS binary file format, are supported by msoffcrypto-tool.
pip install msoffcrypto-tool
From the command line, you might make an unencrypted version of the workbook:
msoffcrypto-tool Myfile.xlsx Myfile-decrypted.xlsx -p "caa team"