Remove a node

root.remove(item)

Add an empty node

root.append(ET.Element('MyNodeName'))

Replace a node with an empty node

    root.remove(item)
    root.append(ET.Element('Strobe'))

Edit an attribute value in a sub node

    for item in root.findall('Position'):
        for item2 in item.findall('MovementBlock'):
            width = item2.attrib['width']    #Get existing value

            item2.set('width', '10')         #Set a new value
            xml_string = ET.tostring(root, encoding='utf8').decode('utf8')    #Output the new XML

Refresh the ElementTree object

You shouldn’t need to. If for some reason you do then you can do this:

    #Get the XML as a string again after the changes we've made
    ET.indent(root, space=" ", level=0)         #Make the XML nice to read for humans (add indents and line breaks)
    data = ET.tostring(root, encoding='utf8').decode('utf8')

    #Reload the xml
    tree = ET.ElementTree(ET.fromstring(data))      #Load the XML as an element tree object
    root = tree.getroot()                           #Get root element