Does windows 10 have SSH already?

Windows does not currently have native SSH support (expected early 2016)

Some further reading here

Here's a more complete answer as of last week:

The PowerShell team is continuing to work on a Windows OpenSSH implementation. Their active work can be seen in this repository which is a fork from the root openssh-portable repository. You can see from the commit history that the PowerShell team regularly merges upstream commits into their repository as well as adding their own commits.

As best I can tell PowerShell/openssh-portable has only modified the upstream code by adding the following folders (and their contained source files) ~/contrib/win32, ~/regress/pesterTests and ~/regress/unittests/win32compat.

On December 19, 2016 the PowerShell team created a pull request into the openssh/openssh-portable repository which is still under review. The most recent activity on the pull request appears to be comments/commits on Jun 13, 2017.

The PowerShell team has a second repository, PowerShell/Win32-OpenSSH, where they make builds of PowerShell/openssh-portable available. The Win32-OpenSSH repo has a few commits of its own but is mostly a source copy from PowerShell/openssh-portable.

You can see the list of Win32-OpenSSH releases here. The releases contain executable binaries of the common openssh commands. If you extract the binaries and then add their directory to your PATH variable you should be able to use them.

What you can do as an alternative is use putty for client side access. If you want something server side, that is a bit harder. But you could use cygwin. There are some articles to get its ssh daemon running as a windows service.