Trump wants big tax cuts for businesses and individuals. He's also planning to roll back regulation and spend more on roads and bridges.
The term 'roll back' can take on two meanings, depending on context.
One definition of 'roll back' is to return something to a previous state. It's a term one often sees in computing - if there is an issue with software for example, the owne/writer might roll back to a previous, known to be working, version of the application.
In broader terms, it can mean to undo something, and that's the intended usage in the example you've given. Trump believes that there are currently too many regulations in place, and they are holding back the economic growth of the USA. By rolling back, or undoing these policies, his aim (misguided or otherwise) is to boost the economy.