Social networks are known to be a big distractions nowadays, and there are different opinions about how to fight them. While some people have manage to completely delete their profiles, this is unfortunately not an option for me because:
Having lived in different countries, I cannot communicate with people I've met through just phone or email. Facebook on other hands offers a nice way for me to keep track of what is going on. It is even something like a customized news feed for me right now - I get to see what news my friends care about.
I believe Facebook is an irreplaceable marketing and customer feedback tool. When you develop a product and have a Facebook page for it, like Google Analytics it offers very interesting insights and also let's you to collect quick feedback from customers.
How I fight distraction? I've identified that the source of distraction in Facebook for me is the news feed. So I have the following two rules for Facebook during my work time:
I'm allowed to look at Facebook only if I get a phone notifications. This usually means a message or a comment directly involving me, so I may allow myself get distracted for that. Bonus rule: if I really need to concentrate, I switch my phone to silent.
Log out of Facebook in your work computer. Facebook app on the phone is enough to do pretty much all you may want to do, so there is no additional benefit from logging into Facebook from your work computer, only distraction of having Facebook one click away.