Removing of VIG and VI's

Dear Team, 

I have many old empty structures in eB V15.6.1 which was imported from other software. These VIG has sub Virtual items linked to them.

There is about a 4 tier level of VIG before the Virtual items is inlcuded in the 4th level. how can i delete the main 1st of 2nd tier VIG with sub groups simultaneously?

Doing them one by one. is a task.

Thank you