Joe Biden kicked off his presidency by obliterating a vast swath of Trump administration measures within hours, even as he steeled his team for a series of bruising fights with business over the economy, starting with a $US15 minimum wage and tax hikes.

Riding a wave of market and popular relief at his inauguration as America's 46th president on Wednesday (Thursday AEDT), Mr Biden wasted no time in signing 15 executive orders.