Actually it doesn't permanently remove it on my model (UE40MU6400). The four Rakuten channels come back and the default app is forced back to TV Plus. Quite what causes that (e.g. firmware update, completely unplugging from power) I don't know. All I do know is that after performing the steps recommended by the Samsung helpdesk (and being assured it would not come back) it did. And my 5 and 8 years old kids saw things they shouldn't have.
Yes Same issue inappropriate adds, #1 worst thing about this otherwise really good TV, but black mark against samsung come on guys fix this. , I deleted the TV Plus channel as suggested in other forums but they have come back.
Deleting the 4000 channels from the list has worked for me so far. Now the cunning barstewards have managed to get round it by forcing the TV onto channel 4000 at switch on, even though the chanbel is no longer in the channel list. I agree with the sentiment expressed here that annoying their customers to this extent is going to destroy brand loyalty. I certainly won't be buying another Samsung TV in future.