How can I turn off limit add tracking

Go to Settings>Privacy> Advertising at the bottom, then turn off Limit Ad Tracking.

Open up the Settings app, go to Privacy > Advertising > Limit Ad Tracking should have a toggle switch there.

If you can't turn it off there is a restriction on your phone, most likely set by your employer who owns the MS Exchange email account that you have installed on your phone. The other possibility is a parental control setting.

But I can't think of any good reason to turn it off. It helps protect you from businesses that want to track your purchases and harass you.