I want to know should I pay for storage on azure even if I don't use it? for example if I store 10TB on an azure VM and then keep that VM powered off, Will Microsoft charge me for that 10TB data? Or it just charges us for powered on VMs?
Questions about products or services pricing are off topic here.
Anyway, yes, you will pay for used storage space even when no one is actively accessing it; the actual price depends on the type and size of the storage. More info here: