Rita... that’s the way political parties work. It’s a convention of delegates. Trumpy should have run as an independent to begin with if he wasn’t prepared to play the game to the end. And, they are not going to change the rules to accommodate him. He thinks he has the leverage to get that done, but he doesn’t. It is what it is.
That's why the outsider who has never run for elective office is the front-runner and has been since July. The majority of Rep voters are disgusted by the political class and their anti-democratic maneuverings. They have been ignoring the will of the people and owe their allegiance to their corporate paymasters. Immigration and trade would never have become issues without Trump.
Trump, Carson, and Cruz (the crusader against the Washington cartel) have amassed 58% of the votes cast and 1,212 delegates to date. The only way the GOPe can thwart the will of the people is at a contested convention where they control most of the delegates after the first round.