Google Nexus 7 (2013) — Activated accessibility talk back. Now unable to cancel it

I activated accessibility talk back and every time I press any button, i get the information read out to me, but I do not know how to go further to the actual button's function. I switched off the tablet, and now when i try to start it by sliding upwords, it just reads out "Unlock button" but does not unlock the screen. How do I get round this and get to the home screen. I want to disable Talk Back. It is too difficult to use,
Please help. I cannot use my tablet for anything at the moment.
Or please tell me where I can find the information on the web from my laptop
I have Android 6.0 on my tablet
Vikram