set_graph_undirected(graph)

# Create a graph with a
# directed tree
graph <-
  create_graph() %>%
  add_balanced_tree(
    k = 2, h = 2)

# Convert this graph from
# directed to undirected
graph <-
  graph %>%
  set_graph_undirected()

# Perform a check on whether
# graph is directed
graph %>% is_graph_directed()