How to solve contact can not remove from skype for business?

after some team mate or colleagues left the team, we might just keep their contacts in our skype contact list. eventually the contact will be displayed as unavailable, when we try to remove them from the list. we click on the confirmation button, but the contact never have been able to removed from list.

the quick solution is very easy and quick.

First  we need to completely exit from Skype applicatio.

Second  launch the outlook portal in light mode

https://outlook.office365.com/owa/?exsvurl=1&layout=light 

 Third click on the Contact Folder on the left navigation panel


Four. Type in contact name in the filter textbox, then select it and delete, then re-launch your Skype for business, we will see those contacts should be all gone.