Disable Extended stored procedure

How to disable extended stored procedure in SQL server 2012 in a single shot?

deny access to it from those you don't want to use it

Which extended procedure do you want to disable?

sp_dropextendedproc 'xxxx' . xxxx is the function name. This command one can run to drop each extended stored procedure function in a user-defined extended stored procedure DLL.

To know more about this, you may check this:
https://technet.microsoft.com/en-us/library/ms164755(v=sql.110).aspx

I might go for disabling an Extended Stored procedure (although it's a better idea to control access rather than disable such things as @gbritton correctly suggested) but I'd be very careful about dropping any such user-defined extended stored procedures. One you drop them, they're gone. Make real sure that you have the verified source code to rebuild them before you drop them because if you find out the hard way that you need then, you'll be in deep Kimchie if you can't rebuild them.