If you did not uninstall Skype then it's almost certainly still there. Click on start and type Skype in the search box. It should also be listed under All Programs. Or are you stating that you have never installed it as it doesn't come pre-installed. The safest and only place you should use is from Skype (Jock1e's link). However watch out that it doesn't add any extras eg Bing search, bing bar. Untick as you go and be careful.
Surface Pro (2017) vs Surface Pro 4