You cannot remove protection from a Word document that requires a password except by using the password. You can, however, create a new document from the protected one and save it without password protection. You will first have to get the document open. This demands workarounds that don't always work or, in some cases, can become complicated. There are also services and tools designed to "unlock" documents but these often come with a financial cost.
Types of Protection and Versions of Word
Determine what kind of protection you are dealing with and what version of Word you are using. Protection can be "read only," which means the document cannot be modified. On the other hand, it may be locked, meaning it cannot be opened. When this is used, the file cannot be accessed without the password. If you lose the password, Word has no option for recovering it.
You will find the security options that allow for these protections in different areas of the Word program depending on which version of Word you are using, such as Word 2003, Word 2007 or Word 2008 for Macs. Approaches to unprotecting the document will differ depending on the version you are using.
If a document is "read only," simply copy and paste it into a new document, either a new Word file or another text program such as Notepad. The document you create won't be restricted. If the document itself is password protected, try opening it as "read only" and following the steps for creating a new document.
Try highlighting the document, right-clicking and using "Open with." Choose a text editor. In some cases, this will open the document. If the document is open but still has password protection, try saving it in .rtf or web (.htm, .html) format. This can remove the protection (because it is now a new document). Keep in mind the file is now in those formats and will need to be saved as new Word document. Also remember that opening files in this way, especially when done as a web page, can cause the document to lose or change the formatting and layout.