public function delete( $id, $slug ) {
		$fn = $this->get_function( 'delete' );

		// Check so the function is callable before using it.
		if ( ! is_callable( $fn ) ) {
			return false;
		}

		// Delete cached value.
		papi_cache_delete( $slug, $id, $this->type );

		if ( $this->id ) {
			return call_user_func_array( $fn, [$this->type, $id, unpapify( $slug )] );
		}

		return call_user_func_array( $fn, [unpapify( $slug )] );
	}