Record company EMI Group plans to lay off up to one-third of its employees and drop artists from its roster, according to published media reports.The restructuring, which could reduce the company's staff from 6,000 to 4,000, was engineered by Terra Firma Capital Partners, the private-equity firm that purchased EMI last year. Citing people familiar with the plans, The Wall Street Journal reported that most of the job cuts would be made in EMI's recorded-music unit, not its music-publishing business. The Journal reported that EMI would announce the changes Tuesday. The Sunday Times of London reported that Terra Firma CEO Guy Hands wanted to drop thousands of EMI artists. EMI artists Robbie Williams and Coldplay are already protesting the plans, according to reports. The company's reported restructuring comes as the music industry navigates a difficult environment. CD sales are in a tailspin, and legal downloads have failed to offset lost CD revenue.