|Rather than duplicate assorted "how to…" etc… - all out there on the www…|
I suggest you run a google trawl/search - using the search term/string:
remove ask toolbar
and you will get more than a few hits… Having had the same pest a while back, at least one the hits you will get will help you get rid of it…
These pests usually arrive when you download and install assorted items. These can be genuine (bona-fide) applications etc.; but presumably they (vendors etc…) get something from whomever to include them in the software…?
Often there is default acceptance of such an item to be installed, and it's easily overlooked… If you accept the "automatic/default" etc. installation - rather than go for "custom" these pest will just go in automatically. But if you elect for/choose to custom install, you will have the options to uncheck install assorted items - and thus avoid them.