The seven-metre high inflatable armadillo was removed from its spot near Brasilia's Esplanade of the Ministries, an enormous boulevard flanked by public buildings, after youths attacked it with knives, Brazilian media said.
Photographs showed a pile of earth and iron railings where the grinning mascot had previously stood.
Last week, another model was damaged after it was attacked during demonstrations in the southern city of Porto Alegre.
Models of the mascot have been placed in several Brazilian cities, including Sao Paulo.
The mascot was unveiled one month ago and a its name - Amijubi, Fuleco or Zuzeco - will be decided by a public vote.
Three-banded armadillos, an endangered species indigenous to Brazil, live mainly in the arid northeast region and are threatened by habitat destruction.
They are unusual among armadillos in that they can roll into a ball to defend themselves from predators.