Deleting Skype for Business Contacts in OWA

Hi all,

 

I have an Office 365 Business Premium account and when I click on the Skype for Business icon on OWA, it shows a long list of 'contacts'. Some of these are actual contacts but the majority seem to be random email addresses - many from servers that I administer and even from some items of spam that didn't automatically get filed in Junk.

 

I can't see any way to delete these contacts, but am I missing something? They seem to roughly match the automatic list of frequently contacted people, but deleting frequent contacts doesn't actually remove them from the list of Skype contacts.

 

I tried the 'light' version of OWA but couldn't find them anywhere in that.

 

Thanks in advance.