If you delete your Steam account, it will not disable your Cross-Save. It will cause you more problems because not only will it not deactivate your Cross-Save, but you also will not be able to authenticate to it TO deactivate Cross-Save later and you will not be able to unlink it from your account. You have to be able to authenticate to do either of those, which means you must be able to log into it, which means it must exist. The Silver restriction on disabling Cross-Save is a security measure. Trying to bypass it in the way you're describing will not only not work, but will cause you additional issues.