Trump has a constitutional right/authority to fire any of his subordinates for any reason. He also had a letter from Rod Rosenstein stating that Comey had committed a number of violations and poor judgement.
Did Strzok have a constitutional power authorizing him to use his authority and power of his office to try to pick a winner for the election and act upon that decision? Get back to me when you can quote the constitutional authority for that.
Trump does not have a constitutional right to obstruct justice, as his comment implied. Get back to me when you when you can treat each issue with the same discernment.