United's U18s are now 12 games unbeaten in the Professional Development League following another victory on Saturday.
A first-half brace from David Parkhouse saw off Watford at Shirecliffe, as United remain undefeated in 2017.
Already assured of the divisional title, Derek Geary's side are keeping the momentum going ahead of the forthcoming play-off's where they will face the runners-up in the south division of the category two clubs.
After a quiet opening half hour, two goals before the break gave the Blades an advantage they never looked like relinquishing.
Firstly, in the 36th minute, PARKHOUSE headed home from a Charlesworth corner, then four minutes later, the Irish striker headed home Ford's inviting left-wing cross despite a tight-angle.
The second-half saw Unied control much of the game and repel the Hornets when necessary to ensure another three points were added to the tally.