Ubuntu – console-kit-daemon – can it be stopped

ConsoleKit manages console logins in graphical mode (i.e. with gdm or equivalent); if your server doesn't have those, you don't need it, but then it won't be started anyway. Also, you may be interested in this question.

But you don't really have 60 instances taking 20% of RAM each. The ConsoleKit daemon is multithreaded, and htop shows a separate line for each thread. It's really one process and there's a single copy of that memory; you can confirm that with ps wwu -C console-kit-daemon.

Additionally, the memory usage shown by htop includes code memory, some of which is likely to be shared with other processes using the same dynamic libraries.