It is stored on the Store table. Go to {yourdomain}/Admin/Store/List ==> edit and uncheck the SSL enabled checkbox. Also, go to General setting {yourDomain}/Admin/Setting/GeneralCommon and uncheck the Force SSL for all site pages checkbox.
If you could not access the website, check the Store table and update the sslenabled value to 0 and check the setting table and update securitysettings.forcesslforallpages setting value to false with the update query in the db and then recycle the app pool and website