There are 2 methods for hiding the C: or any other drive, GPO and a Regedt32 tweak.
There's obvious benefits preventing access to browse the System Drive like being able to Explore to a file and run it. However hiding C: needs to be considered as only part of the solution to prevent access. Its still possible to open PowerShell and cmd then 'cd' without restrictions, create desktop shortcuts to a named file and many others. Even after locking all routes down the audio control icon, assuming the user requires sound control provides a route into browsing the system.
There are,It's# .Synopsis
Remove access to C:
Removes access to the C:\ by setting NoDrives and the value of 4 in the registry or set the User GPO settings 'Prevent access to drives from My Computer'.
#Hides C for all users including Administrator
New-ItemProperty -path 'HKLM:/SOFTWARE/Microsoft/Windows/CurrentVersion/Policies/Explorer' -Name NoDrives -PropertyType DWORD -Value 4
#Hides C for the user the setting is applied against.
New-ItemProperty -path 'HKCU:/SOFTWARE/Microsoft/Windows/CurrentVersion/Policies/Explorer' -Name NoDrives -PropertyType DWORD -Value 4
User GPO Settings