Adding and removing users from SharePoint Clientpeoplepicker

<script src="/SiteAssets/jquery-1.11.2.min.js" type="text/javascript"></script>
<script src="/_layouts/15/clientpeoplepicker.js" type="text/javascript"></script>
<script type="text/javascript">
window.onload = function(){
var userId = "Pass User IDs";
ExecuteOrDelayUntilScriptLoaded(function () {
clearPeopleFieldValue("UserName");
SetAndResolvePeoplePicker("UserName", userId);
}, "sp.js");
};


function SetAndResolvePeoplePicker(fieldName, userAccountName) {
var controlName = fieldName;
var peoplePickerDiv = $("[id$='ClientPeoplePicker'][title='" + controlName + "']");
var peoplePickerEditor = peoplePickerDiv.find("[title='" + controlName + "']");
var spPeoplePicker = SPClientPeoplePicker.SPClientPeoplePickerDict[peoplePickerDiv[0].id];
peoplePickerEditor.val(userAccountName);
spPeoplePicker.AddUnresolvedUserFromEditor(true);
//disable the field
spPeoplePicker.SetEnabledState(false);
//hide the delete/remove use image from the people picker
$('.sp-peoplepicker-delImage').css('display','none');
}

function clearPeopleFieldValue(colName) {
// Select the People Picker DIV
var peoplePickerDiv = $("[id$='ClientPeoplePicker'][title='" + colName + "']");
// Get the instance of the People Picker from the Dictionary
var spPeoplePicker = SPClientPeoplePicker.SPClientPeoplePickerDict[peoplePickerDiv[0].id];
if (spPeoplePicker) {
var ResolvedUsersList = $(document.getElementById(spPeoplePicker.ResolvedListElementId)).find("span[class='sp-peoplepicker-userSpan']");
$(ResolvedUsersList).each(function (index) {
spPeoplePicker.DeleteProcessedUser(this);
});
}
}

</script>