How do you do it?
I do it according to the rules!
(Sorry for the snarkiness... couldn't resist).
Actually, you have a fair question as nowhere in the section about "Destroyed Units
" (7.4.1), does it mention what to do with the hit marker when a unit is destroyed.
As it turns out, that's actually covered in the section about "Rally
" (7.6), where it says:"Hit markers are returned to the Hit Marker draw pile after a unit successfully Rallies or is destroyed."
So unless you would think to look under "Rally" about how to resolve a destroyed unit, you won't find it.
Thanks! Was looking thru the rules but never thought about checking the rally section.