This depends on what permission plugin that you are using. The most easiest way is to remove the inheritance and add those permissions manually to those ranks. However, it is possible to revoke a permission after inheriting from the previous ranks. Check your plugin wiki and look around you will be able to find ways to do so.
However, it is possible to revoke a permission after inheriting from the previous ranks.
I would do this. Add a negated permission node to the group. If you have group1 for instance with kit "group1" and so on and so forth, in group2 I would add permission node -essentials.kits.group1 for example.
PS: Negation inherits as well, so for like group4 you don't need to negate essentials.kits.group1 through essentials.kits.group3. You would only negate essentials.kits.group3.