Error: L6047U: The size of this image (35140 bytes) exceeds the maximum allowed for this version of the linker - How to manage code size?

[Alanarf]

Hi all, 

this is a already known error, and most answers to it is use  Segger Embedded Studio or buy the license or so whatever.

But i wanna know how can i manage the size of my own code?

I know that is the number of libraries or drives i use. But there is some way that i could have my code back running again? What can i do to reduce its size? 

Thanks