'object * contains other objects are you sure you want to delete * object?' When trying to delete retired servers in AD

Hello All,

     I am trying to remove old servers from AD and some state that 'object * contains other objects are you sure you want to delete * object?'. I changed the view and see that theses servers have one or both of these service folders. 

IASIdentity

RouterIdentify

    What is the correct/ clean way to remove these and also ensure there are no issues afterwards. Please advise

thank you

Brian Sawyer