While designing a website recently I needed to disable the parallax feature on one page. As I still wanted it to function on other pages.
To do this you will need to inject a script into the page.
Navigate to the page cog and select advanced and enter the following:
<script> Static.SQUARESPACE_CONTEXT.tweakJSON["tweak-overlay-parallax-enabled"] = false; </script>
Once saved the parallax feature for that page should be disabled.