Hmm? OK here we go. I don't know what ssh-agent does specifically, but I do know what ssh does, it allows you to remotely connect to your computer (usually a server) through a terminal.
Since a large part of the Linux commercial market is on servers, it makes sense to include this program by default, but unfortunately, as clever as it is, any program that allows you to remotely connect to another machine is nirvana for crackers. If you can do it, then eventually, so can they. Thus, ssh is a major attack vector for anyone who might wish to compromise your system.
So you have to ask yourself a few questions. Are you running a remote server? Are you ever going to run a remote server? Will you ever wish to remotely connect to your computer through a command line interface?
If the answer to all these questions is no, then you don't need ssh in any way, shape or form.
So what you do is this. Open your package manager and enter 'ssh' into the 'search' window. If you have any package installed that includes ssh (probably openssh-client) then right click the package and elect to 'completely remove' it.
Your computer will be safer as a result of this action.
Fujitsu Lifebook AH532. Intel i5 processor, 6Gb ram, Intel HD3000 graphics, Intel Audio/wifi. Realtek RTL8111/8168B Ethernet.Lubuntu 13.10,Ubuntu12.10 (Unity), Mint16 (Cinnamon), Manjaro (Xfce).