I have seen only option for up-voting and down-voting. How do I retract a vote?
Your question doesn't specify why you'd want to retract a vote.
If you accidently hit some voting button and you want to undo that, then you indeed have up to 5 minutes to click the voting button to correct your mistake (as in the accepted answer).
And yes, if those 5 mins are passed already, you can only retract your vote from a post after it was edited (also as in the accepted answer).
However, if you want to retract your vote "badly", but the post doesn't get edited anymore (due to which you can't retract your vote), you may want to consider taking advantage of what IMO is a bug on any SE site ... For those users who do have sufficient rep to edit any post (with no approvals required from anybody else), just do an edit yourself. After you did so, you will be able to remove your vote. The bug, IMO, is that in such scenario, such edits should not be taken into account by the SE system to allow you to remove your vote (i.e. the system should look for the last update date of the post by a user that is different from the use who tries to remove his vote).
And BTW, for those who do not have sufficient rep to perform such edits (without approval), just think of "some edit suggestion" that gets approved. After the approval arrives, the same (IMO) bug applies. And don't forget: you only need a rep of "1" to be allowed to suggest edits (though you do need 15, or 125, to be allowed to upvote, or downvote).
Please don't shoot the messenger (about this apparent bug), instead get the bug fixed ...
A bug becomes a feature, right?
PS: voting is assumed to be (a kind of) anonymous. So for anybody who wants to take advantage of this (IMO) bug, you may want to wait "for a while" before retracting your vote (if you don't wait, you'll be the first suspect about which user changed his/her mind about voting).