def METHOD_NAME(self):
    nt = self.id_data
    node_name = self.name
    tree_name = nt.name
    grease_pencil_name = tree_name + "_grease"
    # get grease pencil data
    gp = nt.grease_pencil
    if (node_name in gp.layers):
        layer = gp.layers[node_name]
        layer.frames[0].clear()