Did you resolve to organize your email this year? GMAIL LABELS are just what you need! You can even hide last year's LABELS for a fresh start!
You can hide Labels so that they don't appear in your Label List but they're not deleted. This can be done by clicking the down arrow next to the Label and selecting Hide in Label List. You can also do this by clicking on Settings and Labels. This would be a great way to organize in the new year. You could remove Labels from a previous year so that they don't clog up your Label List but you would still have them for reference.