Leveling up is a permanent action. Most new players level up before knowing the pros and cons to level holding. If they ever want to change their minds and level hold, there is currently only one option-- deleting their account.
I think it would be great if there was another option: spending points! The cost would be 250 points for the first level. After that, the price for a level would go up by 250 points each level, and be capped at 2500 points per level.
When you go down a level, you keep your experience and could level back up to your old level at any time. It would be impossible to go down any lower than level 15.