Student Finance for new Degree

Hello, I have now completed (This past May) one full year of an undergraduate but now want to change to a different degree, I have an unconditional place on this new degree for this September.
I have made a new application for student finance for this new degree but I was just wondering what do I need to do with my old one? I didn't pass the year so I assume they don't expect me to be there in September nor will I be re applying?
Student Finance previously told me I didn't need to withdraw only reapply but I'm not sure now if they understood what I meant.

? I'm not sure why you are asking....

Simply tell your old university you won't be returning and are going elsewhere.

I don't know how to do that, me and my old university haven't had a good relationship and seen as they failed my work I supposed they wouldn't have me re enrolled anyway. I just wanted to know what to do with student finance, the teachers/ tutors don't want to know when it is no longer teaching time so I don't know how I'd even go about talking with them.