This is an example of using pointer of pointer to delete singly linked list element.

hlist_del_example.c

#include <stdio.h>
#include <stdlib.h>

typedef struct node {
  int val;
  struct node* next;
} node_t;

void print_list(node_t* head) {
  node_t* cur = head;
  while (cur != NULL) {
    if (cur->next != NULL) {
      printf("%d->", cur->val);
    } else {
      printf("%d", cur->val);
    }
    cur = cur->next;
  }
  printf("\n");
}

node_t* init_node(int v) {
  node_t* node = malloc(sizeof(node_t));
  node->val = v;
  return node;
}

node_t* append_node(node_t* head, int v) {
  node_t* next = init_node(v);
  head->next = next;
  return next;
}

void delete_node(node_t** cur) {
  node_t* next = (*cur)->next;
  if (next) {
    free(*cur);
    *(*cur) = *next;
    *cur = NULL;
    return;
  }
  free(*cur);
  *cur = NULL;
}

void free_list(node_t** head) {
  node_t* cur = *head;
  while (cur != NULL) {
    free(cur);
    cur = cur->next;
  }
  *head = NULL;
}

int main() {
  node_t* head = init_node(0);
  node_t* last = head;
  node_t* will_be_del_node = NULL;
  for (int i=1; i < 10; i++) {
    node_t* cur = append_node(last, i);
    if (i == 5) {
      will_be_del_node = cur;
      printf("Delete %d\n", cur->val);
    }
    last = cur;
  }
  print_list(head);
  delete_node(&will_be_del_node);
  print_list(head);
  free_list(&head);
  print_list(head);
  return 0;
}