See here:
https://malwaretips.com/blogs/search-myway-com-removal/
Note though that the advice given on that site often seems to go for 'overkill'. Simply running Malwarebytes and removing any unwanted extensions from Firefox should be sufficient. So here's my shortened version:
If you've not already got the free version of Malwarebytes on your computer, download and install it now:
https://www.malwarebytes.com/free/
You used to be able to simply install the free version (and deselect the option to take a trial of the 'Premium' one) but it seems that you now have to accept the Premium trial. (After 14 days it simply reverts to the free version anyway).
Run Malwarebytes and allow it to zap anything nasty which it finds.
Then, in Firefox, click the 'hamburger' (three lines, top right), followed by 'Add-ons'. Select 'Extensions' in the left-hand panel and look for anything which you don't want to be there, clicking 'Remove' to get rid of it.