An 82-year-old concierge at a tony Upper West Side building was slashed in the head with a machete by a disturbed woman let loose despite a slew of prior arrests, cops and sources said.

Hubert Meulens, 82, was left with a fractured skull and 11 stitches after 20-year-old Deashe Calhoun lunged at him in an unprovoked attack, slashing him in the face at Stone Street and Broadway, MTA police and sources said.

“Even with just one blow, I could have passed away,” Meulens said in a phone interview from his Bellevue Hospital bed after his ordeal.

“I’m surprised she wasn’t in prison,” he said of his attacker. “She needs to be away from society for a long time.”

Calhoun was out free after seven prior arrests involving a machete or other weapons, including a similar attack just days ago, sources said. Calhoun was arrested and released after she followed a 31-year-old man and displayed her machete but didn’t use it on Aug. 25, sources said.