It doesn't mean "removal of culture", it's an alien word in the series context.
"A Zentradi expletive statement often spoken to communicate the feeling of shock. Included within the books for the Macross: Do You Remember Love? limited edition remastered DVD set, there's a list of Zentraedi words and their Japanese/English translations. "De culcha" is translated as "stupid thing" or "terrifying thing". By themselves, "de" means "no" or acts as a negative prefix, and "culcha" means "wonderful thing". The closest English approximation would be the phrase "What the hell" in response to experiencing something shocking or bizarre. The phrase can also be used in a positive context, often spoken as a catch phrase for advertising."