int delete_user(const char *name, User **user_ptr_del) {
    
    User *delete_user = find_user(name, *user_ptr_del);

    if (delete_user == NULL){
        printf("user NULL\n");
        return 1;
    }

    // delete user from their friends' list
    for(int i = 0; i < MAX_FRIENDS; i++){
        if ((*delete_user).friends[i] != NULL){
            User *friend = (*delete_user).friends[i];
            for (int j = 0; j < MAX_FRIENDS; j++){
                if (strcmp((*friend).friends[j]->name, name) == 0){
                    (*friend).friends[j] = NULL;
                }
            }
        }
    }

    // free the post the user recieved
    Post *curr_post = delete_user->first_post;

    while (curr_post != NULL){
        free(curr_post);
    }

    // delete user from the user list
    User *curr_before = NULL;
    User *curr = *user_ptr_del;
    User *curr_next = curr->next;

    while (curr != NULL){
        if (strcmp(name, curr->name) == 0){
            if (curr_before == NULL && curr_next == NULL){
                curr = NULL;
            }else if (curr_before == NULL){
                curr->next = NULL;
            }else{ // curr_next == NULL
                curr_before->next = NULL;
            }
        }
    }

    free(curr);

    return 0;
}
From the list pointed to by *user_ptr_del, delete the user with the given name.
Remove the deleted user from any lists of friends.

Return:
- 0 on success.
- 1 if a user with this name does not exist.