Hi,
When you get one ClashResult and find it is a grouo you can iterate each item of this group and remove it by the method
TestsMove(GroupItem, //the source group
Int32, //index that one specific item in the old group
GroupItem, //the target group
Int32) //index that one specific item in the source group
the root folder of the ClashTest is also a group.
you can refer to SDK sample:
\api\NET\examples\PlugIns\ClashDetective\
in line 111 of AddGroup.cs, there is a demo.