I looked into the profile settings and couldn't any button or option for account deletion.
I searched on meta and it seems no one asked this question before, can anyone help me?
should I contact a moderator for this ? thanks:)
First I will ask why do you want to delete your account? Even if you no longer want to use the site you can still keep your account.
There is no way for a user (who has contributions) to delete their account on their own. You have to contact either SE, or a mod.
Ok, so if you really want to delete your account any mod (read me) can delete your account for you. However it does not delete any of your posts, for good reason. You have helped a lot of people, SE does not want all that good stuff to just vanish.
This is what the message for "delete account" says:
Deletes this user account, denormalizes identity on any posts they own, and deletes any negatively voted posts they own. Does not delete any content scored 0 or higher.
Which means any answer or question you have posted will no longer have your name on it (it will say user2816). Your profile page will be gone and if someone still has the url will return a 404.
Comment on my answer, and we can talk about your account deletion, or come by the chat and ping me.