If you use Google Chrome and have any problems such as crashing, unusual startup pages or toolbars, unexpected ads and so on, Chrome officially offers you Chrome Cleanup Tool using which you can solve many of these problems.
As of today it is only available for download on Windows OS only.
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Official Page: https://www.google.com/chrome/cleanup-tool/
Direct Download link: https://dl.google.com/dl/softwareremovaltool/win/chrome_cleanup_tool.exe