Ahmed Awad bin Mubarak was relased on Tuesday, and handed over to local tribes in the southern province of Shabwa.
Dozens of protesters marching in the Yemeni capital, Sanaa, have been beaten back by Houthi rebels who control the capital, witnesses said.
The rebels fired automatic rifles in the air and struck the anti-Houthi protesters with batons and knives, AP news agency reported on Wednesday.
The witnesses said the rebels detained several protesters and journalists, and that around 10 people were lightly wounded in scuffles.
Yemeni newspaper Source Online said that one of its journalists was being held by the Houthis, adding that it considered the group responsible for his safety.
The Houthis seized Sanaa in September and last week put the president, prime minister and top Cabinet members under house arrest, leading to their resignation.
Since then, demonstrations against the Houthis have been held. The rebels detained around a dozen protesters and journalists on Monday.