President Trump with a Republican controlled congress will be able to repeal Obamacare. The controversial healthcare law was passed without a single Republican supporter. The law has been unpopular with many quarters of the electorate. Therefore, the GOP will be able to repeal the healthcare act if it so desires.
If Donald Trump can rally enough support against Obamacare then he will be able to repeal Obamacare but if the decision makers have half a brain they would request a proposal from Trump's team giving a clear and better alternative to Obamacare. Paul Ryan may claim to have a lot of ideas but I think we should see said ideas before any repeal is made.
No, Trump will not be able to repeal Obamacare because the Republicans on the Hill are going to stop him. Paul Ryan is already saying that repealing Obamacare will leave too much of a gap. The Republicans are under the impression that Obamacare has done some good, so they don't intend to get rid of it.
Trump will not be able to repeal Obamacare for obvious reason that Republicans have not offered any alternative to Obamacare. They should first sit down and draft a new health care plan that is much better than the existing one and after it is accepted by people they they can start the processes of repealing the Obamacare.