Trump is not advocating taking it away, I don't get your point.
http://freerepublic.com/focus/f-news/3116989/posts
“Conservative website shuttered after libel ruling [Free Dominion]”
http://freerepublic.com/tag/freedominion/index?tab=articles
Trump is saying he wants to change the libel laws. Current law already allows him to sue for libel. Here is what the article says about current law.
“Under current law, largely determined at the state instead of federal level, public persons, such as politicians, can win a suit against a media organization only if the person can prove that the publication published information with actual malice, knowing it to be wholly incorrect, as well as in cases of reckless disregard. The case that set this precedent — New York Times Co. v. Sullivan — was decided by the Supreme Court in 1964.”
So, if Trump wants to make it easier to sue for Libel then he must be wanting to take away some of the elements that you currently have to prove in order to win a libel case.
Please read post 104. It shows exactly what would happen if we change the law to make it easier for public figures to sue for libel.