Remove all schema from Astra theme.

functions.php

<?php

add_filter( 'astra_schema_body', '__return_empty_string' );

add_action(
    'init',
    function() {
        remove_action( 'astra_masthead_content', 'astra_site_branding_markup', 8 );
    }
);

add_action(
    'astra_masthead_content',
    function () {
        ?>

        <div class="site-branding">
            <div class="ast-site-identity">
                <?php astra_logo(); ?>
            </div>
        </div>

        <!-- .site-branding -->
        <?php
    }
);

// Remove SiteNavigationElement Schema.
add_filter(
    'wp_nav_menu_args',
    function( $args ) {
        if ( 'primary' == $args['theme_location'] ) {
            $args[ 'items_wrap' ] = '<nav id="site-navigation" class="ast-flex-grow-1 navigation-accessibility" role="navigation" aria-label="' . esc_attr( 'Site Navigation', 'astra' ) . '">';
            $args[ 'items_wrap' ] .= '<div class="main-navigation">';
            $args[ 'items_wrap' ] .= '<ul id="%1$s" class="%2$s">%3$s</ul>';
            $args[ 'items_wrap' ] .= '</div>';
            $args[ 'items_wrap' ] .= '</nav>';
        }

        return $args;
    }
);

// Remove class `hfeed` from div#page
add_filter(
    'astra_attr_site',
    function( $attr ) {
        $attr['class'] = str_replace( 'hfeed ', '', $attr['class'] );

        return $attr;
    }
);

// Remove hentry class name from post_class.
add_filter( 'post_class', function ( $classes ) {
    return array_diff( $classes, array( 'hentry' ) );
} );

add_filter( 
    'astra_attr_post-meta-author', 
    function( $attr ) {
        unset( $attr['itemprop'] );
        unset( $attr['itemscope'] );
        unset( $attr['itemtype'] );

        $attr['class'] = 'posted-by author';

        return $attr;
    } 
);

add_filter(
    'astra_attr_commen-meta-author',
    function( $attr ) {
        $attr['class'] = str_replace( 'vcard ', '', $attr['class'] );

        return $attr;
    }
);

// Remove userinteraction schema from post comment meta.
add_filter( 'astra_attr_comments-interactioncounter', '__return_empty_array' );
add_filter( 'astra_attr_comments-interactioncounter-interactiontype', '__return_empty_array' );
add_filter( 'astra_attr_comments-interactioncounter-userinteractioncount', '__return_empty_array' );

/**
 * Remove CreativeWork schema.
 *
 * @param Array $attr markup HTML attributes.
 * @return Array
 */
function astra_child_remove_creative_work_schema( $attr ) {
    unset( $attr['itemscope'] );
    unset( $attr['itemtype'] );

    return $attr;
}

add_filter( 'astra_attr_article-blog', 'astra_child_remove_creative_work_schema' );
add_filter( 'astra_attr_article-page', 'astra_child_remove_creative_work_schema' );
add_filter( 'astra_attr_article-single', 'astra_child_remove_creative_work_schema' );
add_filter( 'astra_attr_article-content', 'astra_child_remove_creative_work_schema' );

// Remove WPHeader Schema
add_filter(
    'astra_attr_header',
    function( $attr ) {
        unset( $attr['itemscope'] );
        unset( $attr['itemtype'] );
        unset( $attr['role'] );

        return  $attr;
    }
);

// Remove WPFooter Schema
add_filter(
    'astra_attr_footer',
    function( $attr ) {
        unset( $attr['itemscope'] );
        unset( $attr['itemtype'] );
        unset( $attr['role'] );

        return  $attr;
    }
);

// Remove WPSidebar Schema
add_filter(
    'astra_attr_sidebar',
    function( $attr ) {
        unset( $attr['itemscope'] );
        unset( $attr['itemtype'] );
        unset( $attr['role'] );

        return  $attr;
    }
);