Deletion not working in binary search tree.

/*           12
                  /\
                 9  15
                / \   \
               4  11   21
The node with data 15 is not being deleted in the above binary serach tree.*/

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

typedef struct Node 
{
    int info;
    struct Node* left;
    struct Node* right;
}node;

void deleteItem(node*,node*,int);
void deleteNode(node *root,node* parent)
{
    node *temp;
    if(root->left==NULL)/*Only left child*/
    {
        if(parent->left==root)
        parent->left=root->right;
        else
        parent->right==root->right;
        free(root);
    }
    else if(root->right==NULL)/*Only right child*/
    {
        if(parent->left==root)
        parent->left=root->left;
        else
        parent->right=root->left;
        free(root);
    }
    else/*Both children exist*/
    {
        temp=root->left;
        while(temp->right!=NULL)
        temp=temp->right;
        root->info=temp->info;
        deleteItem(root->left,root,temp->info);
        free(root);
    }
}

void insert(node **root,int item)
{
    node *parent,*cur;
    parent=NULL;
    cur=*root;
    while(cur!=NULL)
    {
        parent=cur;
        if(item<=cur->info)
        cur=cur->left;
        else
        cur=cur->right;
    }
    if(*root==NULL)
    {
        *root=(node*)malloc(sizeof(node));
        (*root)->info=item;
        (*root)->left=NULL;
        (*root)->right=NULL;
    }
    else
    {
        node *newNode=(node*)malloc(sizeof(node));
        newNode->info=item;
        newNode->left=NULL;
        newNode->right=NULL;
        if(item<parent->info)
        parent->left=newNode;
        else
        parent->right=newNode;
    }
}

void deleteItem(node *root,node *parent,int item)
{
    if(root==NULL)
    return;
    node *cur=root;
    if(item<cur->info)
    deleteItem(cur->left,cur,item);
    else if(item>cur->info)
    deleteItem(cur->right,cur,item);
    else
    deleteNode(cur,parent);
}
    
int main()
{
    int a[]={12,9,4,11,15,21};
    int i;
    node *root,*ptr;
    root=NULL;
    for(i=0;i<6;i++)
    insert(&root,a[i]);
    ptr=root;
    while(ptr!=NULL)
    {
        printf("%d\n",ptr->info);
        ptr=ptr->right;
    }
    deleteItem(root,NULL,15);
    ptr=root;
    printf("\n\n\n\n");
    while(ptr!=NULL)
    {
        printf("%d\n",ptr->info);
        ptr=ptr->right;
    }
    getch();
}