Good friends probably shouldn't become business partners.
You are saying (essentially) that your friend's participation is parasitic.
Do each of you have well defined roles and duties? Do you just expect him to figure out what needs doing? Maybe he is too much of a follower and/or employee mindset type to act independently.
What are his duties supposed to be? Marketing and outreach? The social networking could be viewed by him as a necessity for his job. Given your description, you should determine jointly with him what your roles in the business are.
Assuming that he claims that he is filling the role appropriately, you should quantify the effort that each of you is making toward the business, along with a justification for that effort. Usually (not always) the unit measurement of net effort is hours.
Telling someone that they are wasting so much time every day is always subject to argument - there's no quantification so the other person can always say "no, I don't." Nailing down a list of tasks and/or duty areas and quantifying each person's effort level are a step toward creating a much less arguable contention.
If you can show that you spend 10 hours to every 2 of his on the business then the imbalance becomes very apparent even to him.
As far as separating, good luck on that. It's a lot easier to be selective about your partners up front then to get disentangled from them. In most partnership formats, company assets are owned equally, like marriage. I have anecdotally heard of several startups that were formed in haste with immature members and a small minority winds up saddled with all the work while the rest expect to ride his/her coat tails. The one worker bee is essentially stuck with parasites who will share the wealth and none of the work.
The bottom line is - you may have to buy this person out for cash if you want him to not profit from your work.