The Hemmahallen chain has pulled the masks, worn by the character Ghostface in the popular Scream series of horror films, from its two stores in Jönköping and Värnamo.
“It's a product which you could have sold previously, but you won’t be able to buy one from us, not this year at least,” Andreas Franzén, manager of the stores told Swedish Radio.
“We have no hesitation whatsoever in pulling things from the store which make people uncomfortable or frightened.”
A boy at Råslättsskolan, a school in Jönköping, wore one of the masks when he carried out a knife attack, which left two of his fellow pupils lightly injured at the start of September.
A police car at Råslättsskolan on the day of the attack. Photo: Anna Hållams/TT
The boy had openly boasted on social media that he planned to kill someone in the two months leading up to the attack, sharing pictures of an axe and other weapons he was considering using.
“Don’t worry, I’m not going to kill myself, but I’m planning to kill someone else,” he wrote in a post, the Aftonbladet newspaper reported.
The boy ran home after the attack, where he had time to log on to his computer before the police arrived to arrest him.
”I failed,” he wrote. “I'm going to get seized soon.”
He has since been referred by Sweden's social services to a secure facility for troubled young people.
Franzén told Swedish Radio that he had stopped selling clown masks in 2016, when Sweden was hit by the 'creepy clown' craze then sweeping the world.