Like any other operating system, GNU/Linux has implemented a memory management efficiently and even more than that. But if any process is eating away your memory and you want to clear it, Linux provides a way to flush or clear ram cache.

flush cached memory

  free && sync && echo 3 > /proc/sys/vm/drop_caches && free

I am not 100% sure when you would use this, or what observable issues would prompt the use of this, when I find out I will add them.