Steps:

- Recursively find the node that has the same value as the key, while setting the left/right nodes equal to the returned subtree
- Once the node is found, have to handle the below 4 cases

- node doesn't have left or right - return null
- node only has left subtree- return the left subtree
- node only has right subtree- return the right subtree
- node has both left and right - find the minimum value in the right subtree, set that value to the currently found node, then recursively delete the minimum value in the right subtree

```
public TreeNode deleteNode(TreeNode root, int key) {
if(root == null){
return null;
}
if(key < root.val){
root.left = deleteNode(root.left, key);
}else if(key > root.val){
root.right = deleteNode(root.right, key);
}else{
if(root.left == null){
return root.right;
}else if(root.right == null){
return root.left;
}
TreeNode minNode = findMin(root.right);
root.val = minNode.val;
root.right = deleteNode(root.right, root.val);
}
return root;
}
private TreeNode findMin(TreeNode node){
while(node.left != null){
node = node.left;
}
return node;
}
```