Students for Trump chairman Ryan Fournier first tweeted about the anti-Trump merchandise on Monday.
"As a fierce proponent of the First Amendment that is politically nonpartisan, we recognize Walmart's right to sell the T-Shirts, and the right of consumers to purchase and wear them", the group's executive director Dan Shelley wrote in his letter to the retailer.
Walmart did not immediately respond to a request for comment.More news: Argentina, Portugal eliminated from FIFA World Cup
The items, sold by third-party seller Old Glory, have since been removed from the website.
News of the shirt prompted a #BoycottWalmart movement on Twitter and social media, with a large number of supporters jumping in. By Tuesday afternoon the items appear to have been taken down from the Walmart site.
Other items echoing the anti-Trump sentiment were also available on the retail giant's website, including other T-shirts, coffee mugs and bumper stickers, made by several companies. It pulled merchandise branded with "Bulletproof - Black Lives Matter" after complaints from the National Fraternal Order of Police, and a year ago it removed T-shirts emblazoned with "Rope. Tree. Journalist. SOME ASSEMBLY REQUIRED." that was being sold from its online store past year.
Walmart, not long ago, was in trouble with liberals as well for a shirt it soldthat read "Rope".