我找到了解决办法。我使用了以下脚本：Wordpress Media Manager 3.5 - default link to

并根据我的需要进行了修改：

(function() {
var _AttachmentDisplay = wp.media.view.Settings.AttachmentDisplay;
wp.media.view.Settings.AttachmentDisplay = _AttachmentDisplay.extend({
    render: function() {
        _AttachmentDisplay.prototype.render.apply(this, arguments);
        this.$el.find(\'select.link-to\').val(\'none\');
        this.model.set(\'link\', \'none\');
        this.updateLinkTo();
        this.$el.find(\'select.link-to\').parent(\'label\').hide();

        this.$el.find(\'select.size option[value=full]\').hide();
        this.model.set(\'size\', \'medium\');
        this.updateLinkTo();

    }
});
})();