How to use ToLowe() or ToUpper in Switch statement

I want to limit the cases because they are many. But I don’t know how to use ToLower and ToUpper in switch statement.

public void OnSubmit()
{
    WordInput = nameField.text;

    //Cereal Process
    switch (WordInput)
    {
        case "Take Cereal":
        case "take cereal":
        case "Take cereal":
        case "take Cereal":
        case "Get cereal":
        case "get cereal":
        case "Get Cereal":
        case "get Cereal":          
        case "remove Cereal":
        case "Remove cereal":
        case "Remove Cereal":
        case "remove cereal":
            {

                if (!Cereal1)
                {
                    GameObject.Find("Cereal").SetActive(false);
                    CerealInvent.SetActive(true);
                    CerealBowl = true;
                    Cereal1 = true;
                    mytext.text = "You got it";
                }
                else
                {
                    mytext.text = "You already have it ";
                }
                break;

            }

        case "Take Milk":
        case "Take milk":
        case "take milk":
        case "take Milk":
        case "Get milk":
        case "get milk":
        case "Get Milk":
        case "get Milk":
        case "remove Milk":
        case "Remove milk":
        case "Remove Milk":
        case "remove milk":
            {
                if (!Milk)
                {
                    GameObject.Find("milk").SetActive(false);
                    MilkInvent.SetActive(true);
                    Milk = true;
                    mytext.text = "You got it";
                }
                else
                {
                    mytext.text = "You already have it";
                }
                break;

            }
        case "Get Bowl":
            {
                if(!bowl)
                {
                    bowl = true;
                    GameObject.Find("Bowl").SetActive(false);
                    BowlInvent.SetActive(true);
                    mytext.text = "You got it";
                }
                else
                {
                    mytext.text = "You already have it ";
                }

            }
            break;

Just like this:

switch (WordInput.ToLower())
{
    case "take cereal":
    case "get cereal":
    case "remove cereal":
    // [ ... ]

However if you always expect the word take / get / remove as first word you might want to first split the string on the space character and check them seperately.

string[] words = WordInput.ToLower().Split(' ');

if (words.Length == 2 && (words[0] == "take" || words[0] == "get" || words[0] == "remove"))
{
    switch(words[1])
    {
        case "cereal":
        // [ ... ]
        case "milk":
        // [ ... ]
    }
}