@Sharon1231 if clicking My Account takes you to the homepage, you've logged in with the wrong username. It's possible to have multiple Sky iDs and only the one attached to NOW TV will work. If you've had Sky Broadband or TV in the past your browser may have auto completed your old username. Try other usernames you might use or the forgotten username link on the login screen.
Also you could look through your emails for communications you've had with NOW TV and see if any of these include the correct one, or load the app which you've been watching on and check the settings to see which username is on that.
Once you've got the right one, clicking My Account will show the passes and you can cancel them with a few clicks.
@owlzee cancelling only takes a few clicks. If you are having problems what's going wrong?
This faq should help http://help.nowtv.com/article/How-to-cancel-NOW-TV
why does my history show that i am to be charged after cancelling
just to add to @artesea post above
This help article might explain while you're still being charged
While you should be able to cancel using any device which has the capability to access the now TV website. I would always recommend that cancelling is done using a laptop PC, desktop PC or Mac and not a mobile device. For one thing, it's much easier to see what you're doing on a PC. Be aware that the web browsers used by mobile devices can sometimes contain limitations which can prevent aspects of some websites from working properly. So if you're managing an online account. It's always best to use a proper computer.
To cancel now TV go to the my account button near the top right of any page on the website and select 'my passes' from the list then click the cancel pass button next to the appropriate pass. Remember each pass type needs to be cancelled separately.
After clicking cancel pass you will be taken through a series of dialogues. Follow the dialogues clicking the appropriate option each time. Once you have finished your get a notification confirming that the pass you have selected to be cancelled has been cancelled and you will no longer be charged for it.
If you need further assistance you can contact live chat. To get to live chat click here. Then scroll down to the bottom of the page. Click "contact us" and then click "live chat" there is also an email option
Hope that helps