Unable to Delete "Offline member" from Dell EqualLogic Group

Hi Folks,

Recently one member went offline out of 3 members in Dell EqualLogic Group Manager. OSS tried to come back online, buts it's not coming up anymore.

Model: PS4100

Hence, I tried to delete offline member from Dell EqualLogic Group, But I am getting error message like below.

Note: Still Volumes are mapped to offline member, those volumes also offline anyway.

So kindly provide process how to delete offline member....? and also confirm is it mandatory to delete volumes mounted offline member before deleting offline member...?