When did you take out boost?
Is the “adverts” for NOW/Sky content at the start for 30seconds? If so then they won’t be removed Bt boost regardless.
If it is third party adverts for Tesco or Halifax. Then I would recommend logging out of your device and back in.
If you've added Boost via our website, your account could take up to 4 hours to reflect the fact that you've added it. To get around this, you can trigger your account to update by signing out of the NOW app and signing back in again.
If you added Boost via your Smart Stick, Box, smart TV, PlayStation or Xbox, your account will update straight away and you won't need to do anything.