Withdraw any friend request that you may have sent by mistake-Facebook

If you were going through
someone's profile on Facebook and
accidentally happened to click on “Add
Friend” and then later regretted it, you
can cancel the request.
You might decide
you don't know the person well enough
and so want to withdraw the request.
Facebook doesn’t have an option that
shows you a list of friend requests that
you have sent, so the only way to cancel
it is to go back to the profile page of the
person you have sent the friend request
to. On their profile page you will see
“Friend Request Sent”. Click on this and
in the drop down menu, you will see the
option to “Cancel Request”. It will ask you
whether you really want to cancel the
request, click on “Confirm” to cancel and
avoid a potentially embarrassing social
predicament.