Please follow below steps to Edit file in the cPanel File Manager.
Step-1: Login to your cPanel account and select “File Manager” under FILES section.
Step-2: cPanel File manager will open and now select the appropriate domain/folder if you have multiple websites hosted. Navigate to the correct directory where your file is located.
Step-3: One small “Code Editor” window will Open for the information/notification (Back up your original file before making change). If you have taken file backup please click on the “Edit” button.
Step-4: A below given new window will open where you can edit and save the changes in the file.
Note:- Make Sure you have taken a backup of the file you are going to modify so then you can revert file changes if need.
Now you are done with the changes in the required file.