Yay, found it! I have to go to SmartShare, then recordings,then you have an option to delete. Why you can't do it from the main recordings page, i don't know. Anyway, sorted now.
I've filled up my internal storage and nothing else is recording. I want to delete the previous recordings, but i can't find the option to delete.
I've got a 55UF850T.
I found another previous forum entry, but i don't have those options on my remote or recordings. Maybe that was for an older 2014 TV.
Any ideas?