Lewis Baker smashed into the top corner before Chelsea team-mate Ruben Loftus-Cheek slotted in just before half-time.
Loftus-Cheek then dinked in James Ward-Prowse's pass, with Nathan Redmond sealing the win after a solo run.
England, who have beaten Portugal and Guinea, need a draw against Japan in Friday's final group game to progress.
Even if Gareth Southgate's side were to lose, their rivals would need a huge goal swing to overhaul them.
England have scored 12 goals and conceded just one in their opening three wins, easing past Paraguay after following up a 1-0 win against Portugal with a7-1 thrashing of Guinea on Monday.
They will face either France or Czech Republic in the final.
"The players have set about their work this week with great mentality," Southgate said. "This has been a brilliant experience for them.
"We've shown ruthlessness, great discipline and composure. When you play teams from other parts of the world you have to show a strong mentality to see games through.
"Reaching the final is important but we want to go and win it."
England: Pickford, Iorfa, Chambers, Hause, Chilwell (Targett 39), Chalobah, Ward-Prowse, Loftus-Cheek (Swift 71), Baker, Redmond (Palmer 69), Watmore (Grealish 62). Subs not used: Gunn, Woodrow, Stephens, Grimes, Holding.