Having unused but available credit normally looks good on your credit report. It's like having a reference that someone thinks you're a good risk. So, standard advice has been keep those accounts open, unless the fees are unacceptable.
That being said, many lenders today will profile you through more than a standard credit check. If they suspect that you're liable to binge with your available credit and get yourself in serious debt, they may ask you to close the other accounts before they grant you a loan.
