SA's link is from a reliable website but it's also one which is well-known for its 'overkill' approach to everything.
Simply downloading, installing and running the free version of Malwarebytes Anti-Malware (which is the 3rd of the 5 steps given there) is likely to fix the problem.
However you can't get the free version of Malwarebytes Anti-Malware these days without taking a free trial of their 'Premium' product, which is annoying and has been known to slow some people's computers down considerably (including mine!).
So a better solution would be to download, install and run AdwCleaner. It's now owned by Malwarebytes anyway, so it's just as good but doesn't involve any 'free trial':
https://www.malwarebytes.com/adwcleaner/