Prevent AIOSEO from changing the category to the primary one

add_action(

	'admin_enqueue_scripts',

	function () {

		if ( ! function_exists( 'aioseo' ) ) {

			return;

		}

		// Remove the "Select Primary Category" box from the post editor.

		wp_dequeue_script( 'aioseo/js/src/vue/standalone/primary-term/main.js' );

	},

	100

);

// Prevent AIOSEO from changing the category to the primary one.

add_filter( 'aioseo_post_primary_term', '__return_false' );