If you’re not loading any other scripts from unpkg.com, one (bad) way would be to set a custom Content-Security-Policy header in your reverse proxy setup, and not include unpkg.com. CSP docs: Content Security Policy (CSP) - HTTP | MDN
Edit: Note that this will not remove the <script ... line from the final HTML page, but prevent that script from being loaded at runtime.
But, this is a very hacky way to achieve this. Ideally, there should be a way to disable members completely. Vote for that idea here: Add toggle to turn off members feature