在Qt框架中，QDateEdit是一个用于编辑日期的控件，如果想要删除QDateEdit不是特别好做，如果直接获取QDateEdit中的QLineEdti并设置显示删除按钮（代码如下所示），删除按钮会一直显示，效果并不好，所以继承QDateEdit重新定义样式是比较方便。

QLineEdit *lineEdit = pDateEdit->findChild<QLineEdit*>();
lineEdit->setClearButtonEnabled(true);

 头文件：

class customDateEdit :public QDateEdit
{
	Q_OBJECT
public:
	explicit customDateEdit();
	~customDateEdit();

public slots:
	void slot_clearDate();

protected:
	bool eventFilter(QObject *obj, QEvent *event) override;
	void focusOutEvent(QFocusEvent *event) override;
private:
	void init();
	void updateClearBtnPosition(QLineEdit *lineEdit);// 更新清除按钮的位置

private:
	QToolButton *m_pBtnClear = nullptr;
	QLineEdit *m_pLineEdit = nullptr;
};

源文件：

customDateEdit::customDateEdit()
{
	init();
}

customDateEdit::~customDateEdit()
{
}

void customDateEdit::slot_clearDate()
{
	this->setSpecialValueText(" ");
	m_pLineEdit->clear();
}

bool customDateEdit::eventFilter(QObject * obj, QEvent * event)
{
	if (obj == this->findChild<QLineEdit*>()) {
		if (event->type() == QEvent::Resize) {
			QLineEdit *lineEdit = qobject_cast<QLineEdit*>(obj);
			if (lineEdit) {
				updateClearBtnPosition(lineEdit);
			}
		}
		else if (event->type() == QEvent::MouseMove) {
			QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
			QLineEdit *lineEdit = qobject_cast<QLineEdit*>(obj);
			if (lineEdit) {
				// 计算清除按钮的位置
				int clearButtonWidth = m_pBtnClear->sizeHint().width();
				int clearButtonX = lineEdit->width() - clearButtonWidth;
				if (mouseEvent->pos().x() >= clearButtonX) {
					//如果文本框中有内容再显示
					if (lineEdit->text().size() > 0)
					{
						// 显示清除按钮
						m_pBtnClear->show();
					}
				}
				else {
					// 隐藏清除按钮
					m_pBtnClear->hide();
				}
			}
		}
		else if (event->type() == QEvent::Leave) {
			QLineEdit *lineEdit = qobject_cast<QLineEdit*>(obj);
			if (lineEdit) {
				// 隐藏清除按钮
				m_pBtnClear->hide();
			}
		}
	}
	return QDateEdit::eventFilter(obj, event);
}

void customDateEdit::focusOutEvent(QFocusEvent * event)
{
    //以免失去焦点自动setDate
	QDateEdit::focusOutEvent(event);
}

void customDateEdit::init()
{
	// 获取QLineEdit控件
	m_pLineEdit = findChild<QLineEdit*>();
	if (m_pLineEdit)
	{
		//创建自定义删除按钮
		m_pBtnClear = new QToolButton(m_pLineEdit);
		QIcon clearIcon = QApplication::style()->standardIcon(QStyle::SP_LineEditClearButton);
		m_pBtnClear->setIcon(clearIcon);
		m_pBtnClear->setCursor(Qt::ArrowCursor);
		m_pBtnClear->setStyleSheet("QToolButton { border: none; padding: 0px; }");
		m_pBtnClear->hide();
		
		// 连接清除按钮的点击信号到槽函数
		connect(m_pBtnClear, &QToolButton::clicked, this, &CDateEditWithDel::slot_clearDate);

		// 安装事件过滤器
		m_pLineEdit->installEventFilter(this);

		// 更新清除按钮的位置
		updateClearBtnPosition(m_pLineEdit);

		m_pLineEdit->setPlaceholderText(QString::fromLocal8Bit("选择日期"));// 设置提示文本

		//初始化默认清空
		slot_clearDate();
	}
	setFocusPolicy(Qt::NoFocus);//默认失去焦点，防止光标一直跳动

}

void customDateEdit::updateClearBtnPosition(QLineEdit * lineEdit)
{
	int nClearButtonWidth = m_pBtnClear->sizeHint().width();
	m_pBtnClear->setGeometry(lineEdit->width() - nClearButtonWidth, 0, nClearButtonWidth, lineEdit->height());
}

效果：