A double strike from Greg Pearson and one from Phil Lumsden secured the three points and put Tony Carr's side back in control at the top of their respective group.
Hammers got off to a fine start with an early goal, when Danny Bunce's long-range shot was deflected into the path of Pearson, who slipped the ball under the keeper.
The second arrived 10 minutes before half-time, when Lumsden broke forward from midfield and found the net with a superb chip from just outside the penalty area.
In blustery conditions, Hammers played against the wind in the second half, but still managed to keep control and restrict their opponents to the odd long-range effort. In fact, such was the visitors' domination that Reading didn't manage a single corner-kick in the entire 90 minutes.
Hammers rounded off the victory with a third goal in the 80th minute. Substitute Marce Collington raced down the right and sent in an early low cross that the keeper could only divert on to Pearson, who followed the ball in with his thigh for his second of the match.
Team: Sealey, McClenahan, Tattam, Laws (Parrington 45), Blewitt, Lumsden, Wright (Akinsete 85), Bunce, Morris (Collington 70), Pearson, Cole. Subs unused: Lee, Jackson.
*There was no match for the under-17s today. They begin their play-off challenge next Saturday.