Plugin Help Numeric Config Keys and resetting

How the config will look like:

Code:

player:
warnings:
  1: Grief
    by: AdobeGFX
  2: lel
    by: CONSOLE
  3: k
    by: Player

So i want to save the warnings in a numeric list, like; key1, key2, and key3. And when i remove key2, i want it to reset, so it would be 1, 2, 3 instead of 1, 3. (as shown in the code over)
I've tried with different methods, none of them worked. Would be nice if anyone code help me out
It's not much to say about it, but it should be enough tho.