Setting a file to read-only status helps you to protect the file from changes to the file's content or accidental deletion. 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 (PC) or Control-Click (Mac), 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.