delete an element from a given position in min heap
1, Delete a node from the array
(this creates a "hole" and the tree is no longer "complete")
2. Replace the deletion node
with the "fartest right node" on the lowest level
of the Binary Tree
(This step makes the tree into a "complete binary tree")
3. Heapify (fix the heap):
if ( value in replacement node < its parent node )
Filter the replacement node UP the binary tree
else
Filter the replacement node DOWN the binary tree