If you really want to do this
you can always go into ssh
and pico -w the index.html file
and remove the "change password" html tagging and images.
and/or you can remove/rename the .html file to the change password pages.
Be aware if you use one the cPanel themes, the next time you update your changes may be overwritten.
you can chattr -i the files but I am not sure if cpanel updates chattr + the files.
What I do is I use the Xskin theme, but I download the tarball and rename it and upload it as something entirely different and use that theme. that may the theme's are not overwritten by an update of cpanel.. Hope that helps.