The Ryedale side, without a win in seven games, are now eight points adrift of fourth from bottom Middlesbrough with only three games remaining.
Sheffield took the lead with a penalty and they made it 10-0 at the break with a try from a quickly-taken penalty in the 39th minute.
After half-time Sheffield added a converted try from a break before Malton briefly rallied.
Full-back Sizwe Zondoto make a break and the move was carried on by Kenton Leiataua and Pat Fifita for Leiataua to race over under the posts. The conversion was charged down.
Another quickly-taken free-kick caught Malton on the hop and Sheffield had their third try. With ten minutes remaining, they conjured a fourth try.
A dominant second-half display gave Pocklington a bonus point 36-10 victory at home to Wheatley Hills in North One East.
The game was still in the balance as Pock led 15-10 at the interval, but they pulled clear with three unanswered second-half tries.
Hills opened the scoring and although Billy Hardy equalised for Pock, the visitors regained the lead with a blind side try from a scrum on halfway.
The hosts hit back with two touchdowns in five minutes before the break, teenage prop Jack Helme bursting over from 20 yards, then centre Jack Holbrough joining the pack on a rolling maul to poach the score, Hardy converting.
Wing Tim Nixon powered over in the corner only to put a foot on the line in-goal, but Pock were not to be denied as Helme went on another charge and number eight Marcus Britland followed up to plunge over.
More slick offloading freed Nixon on the left and this time his touchdown was good. Then replacement back row Ben Stephenson went clear on the right and hooker Dave Birch was in support to score at the posts.
Hardy added all three conversions as Pocklington coasted home.
Josh Cruise helped himself to 25 points as Selby beat basement side Acklam 60-24 in Yorkshire One.
The victory ensured Selby held on to fourth place, although they allowed Acklam to snatch a four-try bonus point by losing the plot in the last five minutes.
Flanker Rihi Brown returned to the squad and scored a hat-trick of tries off the bench, the first of which came from his first touch.
Cruise touched down twice and kicked six conversions and a penalty, while there were also tries for Martin Protheroe, Ben Lunt (2) and Charlton McCoy.
York suffered an agonising 22-20 defeat at sixth-placed Old Brodleians in Yorkshire One.
York RI lost 10-0 at Halifax Vandals in a Yorkshire Four game played in atrocious conditions.
The only first half score was a penalty to the home side. RI hammered the Vandals' line but were kept at bay by the hosts.
A wayward kick gifted Halifax a converted try.
RI's man of the match was Frazer Land.