Following Massive Amounts of People on Tumblrby James Wright
Tumblr lets you follow large numbers of bloggers, but there are different limitations in place that affect how many people you can follow in one day and overall. Most users won't hit Tumblr's rather generous follow limit, but if you decide you need to clear out the list of blogs you are following or make room for new blogs, you can unfollow anyone at any time.
Tumblr lets you follow up to 5,000 total blogs. Note that this limit is not extended across any additional blogs you may have, even if they are attached to the same email address; each of those blogs can follow 5,000 blogs as well. You are also limited to following up to 200 blogs per day, so choose who you follow carefully. Follow limitations apply only to how many blogs each person can follow; there is no limit to how many people can follow a blog.
You can view everyone you currently follow and unfollow people from the same place. Open your dashboard, then click "Following X blogs" where "X" is the number of blogs you are currently following. Click "Unfollow" next to any of their names to remove them from your list. Alternatively, if you see a post by someone you want to unfollow on your dashboard, hover over his user icon until his user panel pops up, then unfollow him from there. However, if you are trying to unfollow a large number of people, the former method is faster.