Setting a file to read-only helps you to protect the file from accidental deletion and changes to the file's content. If a file is set to read-only, you will not be able to save changes to it unless you turn off the file's read-only status.
Find the file you want to edit.
Right-click the file, and then click Properties.
Click the General tab, clear the Read-only check box, and then click OK.
Edit and save your file as needed.
If you do not want to change the read-only status of the file but you still want to make changes to the file, you can save a copy of the file with a different name, and then save changes to the copy.