How can I do the activation lock off my iPhone?

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

You either need to remember the user name and try to reset the password OR you can contact support by using the button in the top right of the page. You will need proof of purchase of your device, usually the sales receipt for the original point of sale and they can attempt to assist you if you have exhausted all other attempts to locate your login details. I do urge you to attempt to locate your login details because otherwise you will lose a great deal of information to include your contacts, calendar events, notes, photos, text messages, app history and data.