Block user from mapping to \\hostname\c$

Question 1
I have a group of technician that have local right to local computer.
How do I block them from mapping to remote computer c: drive without unsharing the  default c$
example: \\hostname\c$

Question 2
I have a group of technician LOGON TO DOMAIN and have local right to local computer
How do I block them from mapping to remote computer c: drive without unshare the c$
example: \\hostname\c$