Whats wrong with my code?

Assignment was to implement print reverse, remove, and to print an actual tree for this binary search tree class. here is my output when i ran the tester class that i made. The reverse order isnt working, and getting an weird error when i try to remove. everything is compling okay though. have not gotten to printing the tree because i wanted to get the print reverse and remove out of the way first.

*** looking for tips, lines to fix/what i did wrong, please try to avoid changing all the work i did.

public class MyTree{

private TreeNode root; public MyTree(){ root=null; } public void remove(int data){ //implement this method to remove a node with the same data value TreeNode focusNode = root; TreeNode valueNode = null; // will be variable to keep track of the node containing value we are removing if (root == null){} // cant remove anything if root is null else valueNode = removeHelper(focusNode, data); // to delete node if it has 0-1 children if (valueNode.getLeft() == null){ valueNode.setData(valueNode.getRight().getData()); //= valueNode.getRight().getData(); TreeNode temp = valueNode.getRight(); //valueNode.getRight().setData(null); temp = null; } else if (valueNode.getRight() == null){ valueNode.setData(valueNode.getLeft().getData()); //= valueNode.getLeft().getData(); TreeNode temp = valueNode.getLeft(); //valueNode.getLeft().setData(null); temp = null; } // to delete if it has 2 children or the root else if (valueNode.getLeft() != null && valueNode.getRight() != null){ valueNode.setData(getSuccessor(valueNode).getData()); //=getSuccessor(valueNode).getData(); TreeNode temp = getSuccessor(valueNode); //getSuccessor(valueNode).setData(null); temp = null; } } // end method // will find successor if valuenode has two children private TreeNode getSuccessor(TreeNode node){ TreeNode temp = node.getRight(); // temp node is the one to the down>right of the one we are trying to replace while(temp != null) temp = temp.getLeft(); return temp; } // searches through tree until it finds the node with the value, then returns the node private TreeNode removeHelper(TreeNode node, int data){ if (node.getData() == data) return node; else if (data Re printed in order: 12 25 30 31 40 47 50 68 tree size is: 8 printed in reverse: 68 50 12 25 30 31 40 47 After removing 40: Exception in thread "main" java.lang.NullPointerException at MyTree.remove (MyTree.java:27) at MyTreeTester.main (MyTreeTester.java:20)