Removing whatsapp documents from Ipad after Migrating from iphone

Hello all:
I purchased Ipad mini 4, and i setup my IPad from my Iphone.
everything went fine, except the whatsapp data.
I now have more than 15GB of whatsapp documents on my Ipad, and i can not open the whatsapp on Ipad, also can not delete it's document.
i went to settings/general/Ipad storage/whatsapp and i found it's documents, but there is no delete or remove there like other apps.
is there a solution for this?
Any help will be highly appreciated.