Dropbox: don’t sync certain directories; empty the cache

Problem
I have a laptop with a small HDD. I want to use Dropbox on it too but in this case I hardly have any free space left. Could I select certain directories that I don’t want to see on my laptop?

Solution
Yes, it’s possible. Here is a detailed description how to do that. In short: go to Dropbox -> Preferences…, select the Advanced tab and click on Selective Sync… Here untick the directories that you don’t need on your current machine. When you click on Update, these directories will be removed from your local Dropbox folder but they remain on the server, so there is no need to worry. They are simply not synced with the current machine.

However, you may notice that after Dropbox has removed these directories, you still don’t have more free space :( Well, the dropbox client put the deleted files in the cache… Here is how to empty the cache. In short: stop the client, delete the content of the cache folder (but leave the cache folder itself), restart the client.