Nobody has a “right” to walk away from pledges.
First, I think you need to ask who walked away from the pledge first?
Trump signed a pledge On September 3rd with the reassurance that the GOP will treat him like any other candidate and will support him if he was the eventual nominee.
Several high level members have conspired against Trump. Both Kasich and Cruz have already said that they will not support Trump if he was the nominee. They have reneged on their part of the pledge. I fully support Trump on this decision. He got nothing from signing this.
Can you honestly say he has been treated fairly by the GOP?
Look, you are either a man of your word or you aren’t. Trump evidently is not. And it appears neither is Cruz or Kasich.