Hi,
To delete Snapshot:
In Azure portal, navigate to Snapshots using link below:
Click on the name of the snapshot you want to delete
Click Delete button and click OK when prompted.
To delete Disk:
In Azure portal, navigate to Disks using link below:
https://portal.azure.com/#view/HubsExtension/BrowseResource/resourceType/Microsoft.Compute%2Fdisks
Click on the name of the disk you want to delete
Click Delete button and click OK when prompted. If the Delete button is disabled then the disk is likely attached (check Disk state on this screen) to a VM and can't be deleted. You will need to detach the disk from the VM or delete the VM so that you can delete the disk.
If the above was helpful please click Accept Answer.
Thanks.
-TP