var i = 28;
var checkBox2 = document.getElementsByTagName("input")[11];
var checkBox3 = document.getElementsByTagName("input")[12];
var checkBox4 = document.getElementsByTagName("input")[13];

function clear () {
    if (i <= 29) {
        document.getElementsByTagName("li")[i].click();
        i++;
    
        setTimeout(arguments.callee, 600);

if (checkBox2.checked = true ) {checkBox2.checked = false};
if (checkBox3.checked = true ) {checkBox3.checked = false}; 
if (checkBox4.checked = true ) {checkBox4.checked = false}; 

} else {
        alert('Готово!');
    } 
}clear();