How to remove numbering from subitems?

I can start numbering all subitems by prefixing the leading item with [1].
What prefix can I use to stop numbering further indented subitems?
I only what the first level subitems to be numbered, and not the second level ones.

This is what I need:

Remediation
  1. Solution A
        Detail x
        Detail y
  2. Solution B

This is what I am getting:

Remediation
  1. Solution A
        1.1 Detail x
        1.2 Detail y
  2. Solution B

I’m afraid, there is no way to remove number prefixing for subitems, at least an easy one.

I’ve created a corresponding request in uservoice - https://checkvist.uservoice.com/forums/2121/suggestions/40261591, cannot promise a quick fix, sorry.

Best,

CSS classes could help to style (or in the case: hide) the numbers.