Two problems with that idea:
1. Repealing without replacing would increase the uninsured by 18 million the first year and 32 million over the next decade   https://www.cbo.gov/publication/52371
 
and 

2. Obamacare basically is the Republican health care plan, relying on the private insurance markets and personal responsibility, designed by the Heritage Foundation and first implemented by Gov. Romney. They don't have any other realistic alternative.