You seem to be ignorant of all the executive orders he has issued and all the other transfers of power he has effected from the legislative to the executive branch. Not only the czars, which is bad enough, but the unprecedented power he has given to agencies and other parts of the executive.
He has not been hamstrung by a Republican Congress. Not that they aren’t trying. For criminy’s sake, read up on it. And read some European history of the thirties while you’re at it.
Any executive order can be rescinded immediately. An executive order, fwiw, is simply an executive’s decision position on how he will or won’t handle a given situation/law.