Antd的多选框中，如果需要移除已选中的项，可以使用filter方法来过滤掉已选中的项。具体实现的代码如下：

import React, { useState } from 'react';
import ReactDOM from 'react-dom';
import { Select } from 'antd';

const { Option } = Select;

const MultiSelect = () => {
  const [value, setValue] = useState([]);

  const handleChange = (val) => {
    setValue(val);
  };

  const handleRemove = (item) => {
    const newValue = value.filter((v) => v !== item);
    setValue(newValue);
  };

  return (
    
      Item 1
      Item 2
      Item 3
      Item 4
      Item 5
    
    {value.map((item) => (
      
 handleRemove(item)}>Remove {item}
    ))}
  );
};

ReactDOM.render(, document.getElementById('root'));