Just add a raw html underneath the scorm module in which you add a css snippet that renders the button hidden or invisible. (You need to check the name of the css class of the button.)
The scorm-xblock is hosted by Open edX LTI provider and I don’t have an idea to access the Scorm module on which I can add the suggested raw html to access the html elements like the Fullscreen button.
Since this scorm-xblock is hosted from another domain, accessing the iFrame elements will trigger a CORS security issue.