Similar to protecting a workbook, you can protect a word file with a password so no one can view the document if they do not have the password. Protecting with a password is different from restricting editing a word file, which you can still view the file even you do not have the password. Please see below for details:
Step 1: Click the "File" tab from the ribbon;
Step 2: From the "Info" section, click "Protect Document";
Step 3: Click "Encrypt with Password" from the drop-down list;
Step 4: Type a password in the password box, and click "OK";
Step 5: Retype the password to confirm your password and click "OK" at the bottom;
Step 6: Save the word document either using "Ctrl+S" or click the "Save" button from the ribbon.
How to Unprotect a Word Document
To unprotect a word document protected with a password, you will need to know the password to open the file first. After you open the file with a password, you can repeat the above step 1 to step 3.
In step 3, instead of typing a password, you need to delete the password in the box and leave that box blank, then click "OK" at the bottom.
Once all the above is completed, click "Save" button from the ribbon, or shortcut "Ctrl+S" to save the changes.