How do I get rid of Wow.com it over rides fire fox

Go to the Add-ons and Options, check up whether links or extensions related to the website exist and remove them. Also check the search engines and remove any unwanted search engines. Here is [a blog] which provides you with more removal methods.

edit: removed blog link. Besides this is a Mac user and not Windows.

Mac Malware Scanners https://discussions.apple.com/message/29938930#29938930

You can also try https://www.malwarebytes.org/antimalware/mac/index.html