Since you have a positive payment history with the cards, it may not be a good idea to close the accounts. If you simply want to prevent yourself from using them, you can always pull the old trick of freezing the cards in a block of ice?or better yet, just put them away where you will not be tempted to use the credit.
Any accounts that have a long, positive payment history should have a positive influence on your credit score. Also, since you already have good credit, there is no need to make any changes to your credit profile, since the effect of changes are often unpredictable. You especially want to avoid any damage to your credit since you are planning to purchase a home in the near future.
If you are happy with your current credit score, keep doing what you are doing. After you purchase your home, you can reconsider closing those unwanted accounts. At that point, even if your credit score is negatively affected, the financial repercussions will be less severe.
Best of luck,