The Subway sandwich chain is no longer letting store owners walk away mad.

Now the embattled chain is suing former owners of shuttered shops for the remaining rent on their leases, The Post has learned.

The change of tack by the Milford, Conn., company comes as the struggling business — the country’s largest restaurant chain — faces a growing number of store closures.

The stepped-up hostilities were clear in a lawsuit Subway filed against the former owner of two Manhattan restaurants.

Subway sued the owner, Suresh Peddu, for more than $150,000 in rent remaining on the leases of his 56th Street and 14th Street stores, according to papers filed in Manhattan state court.

Peddu is fighting back.

He said he closed his money-losing stores after Subway’s marketing bungles — like when it was found that its bread contained yoga mat chemicals and when company spokesman Jared Fogle pleaded guilty to having sex with minors — chased customers from his stores.

Profits then turned to losses, according to court papers. Peddu said he therefore shouldn’t have to pay the remaining rent.

Subway not only rejected Peddu’s argument but also threatened to seek damages from the former shop owner for disparaging its reputation if those counterclaims weren’t withdrawn.

After Subway threatened him with losing more money, Peddu withdrew the claims, court papers show.

Until recently, Subway never went after franchisees who closed stores, a former Big Apple franchisee told The Post.

“Franchisees were always told not to worry,” the franchisee, who spoke on the condition of anonymity, said.

But that was then.

Now, with McDonald’s and other fast food chains stepping up their game — and smaller sandwich shops stealing customers by marketing themselves as having fresher ingredients — traffic to Subway restaurants has fallen 25 percent over the past five years, according to internal documents seen by The Post.

Perhaps half the New York City locations are losing money, the former franchisee said.

Subway in 2017 filed at least 12 suits in Big Apple courts against former restaurant owners who have closed up their shops, according to court records.

The suits seek money to cover rent for the unexpired leases.

“Subway has always addressed all violations of franchise agreements or subleases on a case-by-case basis,” a Subway spokeswoman said.

“In the case of Peddu, he essentially disappeared for more than a year after failing to pay rent and related charges on two Subway restaurants,” the Subway spokeswoman said.

Peddu, in a handwritten answer to the suit, said he had been a franchisee in good standing since 2002. “The main reason for these store closures is … primarily due to Subway corporate,” he said in his initial answer to the suit.

Peddu declined to comment to The Post.