Morganella posted an offensive message after Switzerland lost 2-1 to Korea on Sunday.
The Swiss Olympic hopeful was booed throughout the football match after he picked up an “injury” in a phantom challenge with Arsenal forward Park Chu Young.
After the game, Morganella vented on Twitter, writing: “I want to beat up all South Koreans! Bunch of mentally handicapped retards!” (“Je les tous Defonce Coréens, allez vous tous Bruler, bande de trisos”)
A backlash erupted on Twitter, prompting the 23-year old to issue and apology and delete his Twitter account.
“I made a huge mistake after a disappointing result,” Morganella said.
“I wish to apologise to the people in South Korea and their team, but also to the Swiss delegation and Swiss football in general.”
Earlier this month, Greek triple jumper Paraskevi Papachristou was expelled from her country’s Olympic team over comments she posted on Twitter were labelled racist.