How do I clean inside my fridge?

[Neverendingdust]

I’m in the process of doing a deep clean of the kitchen and the fridge is next on the list. I’ve removed the glass shelves to put in the dishwasher but the inside back panel which sometimes has frost on it now has a grey hue with streaks, I’m presuming it’s black mould? How exactly can I clean it?

Bleach/antibacterial spray and wipe
Or make a bleach/washing up liquid solution and clean with a cloth