You should close down the credit accounts you don't use!

Hi i have a experian credit socre of 999, but it says on my checks that i have a few credit accounts, which i owe nothing on and it says i have debt of 5000 on available limit of 26000, should i close the ones i don't use or leave them open to show how little debt compared to available, which is the way to go, i'm thinking just close them down but i've just put an offer on a house and want want to jepodise my credit when the mortgage application goes through.

Confused?