There are a plenty of places we'll tolerate ads, but desktop apps displaying our contact lists might feel like a bit much to you. If so, you can disable the contact list ads within Skupe in a buried setting.
Somehow we never knew this option was there, probably because it's in a weird spot. In Skype for the desktop, open up the Options box. Under the notification subsection, click "Alerts & messages". Here, you'll see a checkbox labelled "Promotions" Uncheck it and you're ad-free. Simple as that. Hit the link for some other cool, lesser-known Skype tips from the How-To Geek.
7 Skype Tips for Power Users [How-To Geek]