how do I unmergre?

Hi K,
Unmerging is a curator tool not available to general users.
Rather than unmerging Phillip (assuming the merge was accurate) i think what you would find helpful are these two options that are available from the Settings "cog wheel" when in TreeView:

Changing the number of generations displayed is probably the best option but you could also select "direct ancestors only" as this hides siblings, any of these options will improve your experience without affect anyone else.