Simply disabling the service will effectively remove the vulnerability, but at the cost of losing the ability to share folders, it's not the optimal choice at all.
The best course of action is to apply the security patch that fixes the bug and prevents the spread of the virus without disabling anything. You need to download
KB4012212 and apply it to get rid of the vulnerability. You can download from the link or though Windows Update.
If you still want to disable SMBv1 altogether, go to start => type services.msc => find the "server" service, stop it and set it to disabled. It doesn't appear in the Windows features because SMBv1 isn't a feature, is a protocol, and the server service is what implements it.
Sorry but I had to sign up just to respond to this as it's quite a way off the mark :shock:
I'll agree that installing the KB4012212 hotfix is definitely the best way to go
But in terms of your original question
Disabling the server service as advised above
totally disables SMB and as also mentioned above it's correct that you'll lose the ability to share files
But there is
no need for a measure that extreme
There are three "dialects" for SMB
The vulnerability applies to SMB1
SMB 2 and SMB3 are
not affected
So as long as you have a version of Windows that supports the newer SMB versions you can disable SMB1 (basically anything higher than Windows XP and Windows Server 2003)
Microsoft has a comprehensive write up of how to do it here
https://support.microsoft.com/en-gb/help/2696547/how-to-enable-and-disable-smbv1-smbv2-and-smbv3-in-windows-and-windows-server
It IS a feature that you can you enable/disable in Windows 8.1, Windows 10, Windows 2012 R2, and Windows Server 2016
For everything else it's a couple of commands or a registry entry
note you have the option for disabling SMB1 for;
the server (a computer where files are shared from)
the client (a computer used to access files on a server)
A windows machine can be both of these things so you have the option of disabling one or the other (i've done both on my networks)
Knock on effects to consider....
Some devices only use SMB 1 (photocopiers that do scan to folder, older NAS devices, etc)
Any questions feel free to ask...