The two widemen have started just one game apiece since the Londoner took charge at the John Smith’s Stadium in September and their exit follows that of Jon Stead to Bradford City on Thursday.
Ward is likely to have played his last game for Huddersfield due to his contract expiring in the summer but Hammill still has 18 months remaining on his own deal.
Anthony Gerrard, whose only appearances under Powell have come amid an injury crisis at the back, is another expected to head out of Huddersfield during the transfer window amid interest from Major League Soccer clubs Toronto and Orlando City.
Getting four of the larger earners off the wage bill will be a major boost for Powell, who, after assessing his squad over the past four months, is ready to make a couple of additions.
A striker remains a priority, especially with Burnley understood to be monitoring the form of both top scorer Nahki Wells and James Vaughan in recent weeks and Grant Holt having returned to parent club Wigan Athletic after a loan spell.
As important as he believes freshening up the squad is this month, Powell’s main focus is today’s visit of Watford.
He said: “It will be an open game against Watford and I think we are better in those. We like to play our stuff and we have been good at it, in the main, at home.
“Our last League result (a 2-1 win over Bolton Wanderers) was a pulsating, terrific open game and I thought we deserved the three points. That is how we have to play.
“I watched Watford at Chelsea on Sunday and they are very assured. They have some good players all over the park, lads like Troy Deeney.
“We have got to stay strong and resolute and defend well, both individually and as a unit.
“They will come here to attack and we will have to be ready for that. But, equally, I think we can attack them. We will be fully prepared to play our part in what is hopefully another home win against a good side.”
Watford have won four of five meetings between the two clubs since Huddersfield won promotion from League One in 2012, including both games at the John Smith’s Stadium. Jonathan Hogg will be missing against his former club after being sent off in the FA Cup loss to Reading.