How can I free that extra consuming memory space by system in lumia 520?

[Windows Central Question]

My lumia 520 with windows 8.1 denim is consuming more than 3GB memory space but actual size of windows 8.1 is 1.5GB, How can I free that extra consuming memory space?

 

[Harrie-S]

Not, 3Gb is a normal size for system memory.