Bleeping Computer is NOT a sketchy site, it is one of the most respected sites for Security and virus cleanup on the web. Here is a more direct download link: https://www.malwarebytes.com/adwcleaner
Why would you ever need to replace your computer if it gets infected? That is software which can always be cleaned up or reinstalled. A computer is hardware, but even if you have hardware fail (which you cannot from a virus) that can also be replaced. That's like saying you would have to replace your car because it got dirty. So please keep asking back questions that you have so we can clear up any other misconceptions.
I think that web provider has somehow gotten you to set it as Home or Start page. Did you check what page is set for both of those?
https://www.tenforums.com/tutorials/144209-how-...
https://www.howtogeek.com/684345/how-to-change-...
Keep me posted on your progress as I will be here to help until the case is resolved.
______________________________________________
Standard Disclaimer: There are links to non-Microsoft websites. The pages appear to be providing accurate, safe information. Watch out for ads on the sites that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the sites before you decide to download and install it.