A Microsoft Excel document saved in a version of Microsoft earlier than 2007 could automatically lose its password when opened in OpenOffice Calc. If you're trying to remove the password or other protection from an Excel document with OpenOffice Calc from a 2007 or later version, however, it becomes a little tricky. But there are a couple options you can take to remove protection from an Excel document, making it so that anybody can use it.
Open the document by double-clicking on the icon on the desktop or in the appropriate folder. If it prompts you for a password, enter it.
Click "File" and "Save As." Choose the option that saves the file with the ".xlt" extension. Uncheck the option in the bottom left corner that says "Save with password." Press "Save." This removes the password protection.
Click the "Tools" menu and choose "Protect Document." Either the "Sheet" or "Document" option may have a checkmark next to it. Uncheck it. You may need to enter the password. This will unprotect the entire document. Verify this by typing in one of the cells. If you can type in the cells, they are unprotected. Save by pressing "Ctrl+s."
If you don't know the password, you cannot open the document or remove it. You'll need to buy a special program to remove the password.