Try to run a function only on Home

You’re calling it on the wrong hook, and you’re calling the wrong conditional function to test.

When the after_setup_theme hook is fired, WordPress hasn’t finished processing wether you’re on a page or a homepage yet.

You should also never pass in hardcoded post IDs. In this case is_home works, as might is_front_page. If you really must reference a hardcoded posts, and I beg that you don’t, use a post slug instead, or even better, store a post ID in an option and present a drop down menu to let the user choose in the backend.

Your function should be something like this:

function removeP(){
    if ( is_home () ) {
        remove_filter('the_content', 'wpautop');
    }
}

add_action( 'template_redirect', 'removeP' );