I hate loose ends, especially financial loose ends.  If you have old accounts that you no longer use like credit cards, home equity lines or other bank accounts, you should close them.  In case you need convincing, I've created a list of the reasons you should close unused accounts.
When ING kept sending me statements [...]

FICO scores don’t matter to wealthy people. I know, that sounds like heresy but it’s true. The truly wealthy (or those that will be wealthy someday) know that their credit scores (and credit bureaus) really don’t matter in the long run.
Wealthy People Don’t Worry About Credit Scores
A FICO score or any credit score [...]