How to fix sh 1 cls not found in C programming

/tmp/Cj8Pv0jRVQ.o
sh: 1: cls: not found
computer
=======================

[1] HP Pavilion		php 3,500.00
[2] ChromeBook		php 2,500.00
[3] Acer Aspire		php 4,500.00
[4] HP Ram 16GB		php 500.00
[5] chromeBook Ram 32GB		php 750.00
[6] Acer Ram 64GB		php 1,500.00

Enter Code	: 

// ASDIGNMENT 1
#include <stdio.h>

void main (void)  {
    int code, qty;
    float price, amt, totalAmt, cash, change;
    char addAnother;
    
    // do-while loop -> post-test
    // while loop -> pre-test
    // for loop -> pretest
    
 do {
    system("cls");
    printf("======================\n");
    printf("computer\n");
    printf("=======================\n\n");
    printf("[1] HP Pavilion\t\tphp 3,500.00\n");
    printf("[2] ChromeBook\t\tphp 2,500.00\n");
	printf("[3] Acer Aspire\t\tphp 4,500.00\n");
    printf("[4] HP Ram 16GB\t\tphp 500.00\n");
	printf("[5] chromeBook Ram 32GB\t\tphp 750.00\n");
	printf("[6] Acer Ram 64GB\t\tphp 1,500.00\n");
    
    printf("\nEnter Code\t: ");
    scanf("%d", &code);
    printf("nEnter Quantity\t:");
    scanf("%d", &qty);
    
    switch(code) {
        case 1: price = 3500.00;
                break;
        case 2: price = 2500.00;
                break;
	    case 3: price = 4500.00;
		        break;
        case 4: price = 500.00;
                break;
		case 5: price = 750.00;
		        break;
		case 6: price = 1500.00;
    }
    amt = price * qty;
    printf("\nAmount\t\t: %.2f", amt); 
    
    totalAmt = totalAmt + amt;
    printf("\nTotalAmount\t: %.2f", totalAmt);
    
    printf("\nAdd another oder(y/n)? ");
    addAnother = getchar();
	addAnother = tolower( addAnother );
    }while(addAnother == 'y' || addAnother == 'Y');
    
    do{
        printf("\nCash Tendered\t: ");
    scanf("%f", &cash);
    }while(cash < totalAmt);
        
    
    change = cash - totalAmt;
    printf("\nChange\t\t: %.2f", change);
    
}