Of course the President can obstruct justice.  A President cannot violate the law, cannot prevent a violation of the law, cannot order people to lie under oath, cannot destroy evidence of wrongdoing, etc etc etc.  Now you argument is that somehow the President is a monarch, that no law can touch them, that the President is imperial.  To quote Nixon who you seem to want to emulate,  "Well, when the president does it, that means it is not illegal."  None of that is supported by the Constitution, nothing you are arguing is supported by the Constitution.  It is a High Crime, to obstruct Justice.  The Congress and the President have passed laws making obstruction illegal.  These laws are not ones that a present is exempt from, unless the Constitution exempts him.  And in this case no exemption exists.  Please explain how the President, is exempt from this statute: https://www.law.cornell.edu/wex/obstruction_of_justice