How to Make Spotify the Default Music Player in CM13? I cannot find any setting for the feature in Settings. 
I want Spotify takes over the buttons' actions in the lock screen. So drawing the next symbol should play Spotify's song instead. I do not want to remove the built-in one (Eleven). 

Phone: Oneplus 2
OS: Cyanogenmod 13
Related: How to set Spotify as default Music Player?
How do you want it "default"? Play music when clicked file in a file manager, or take over media button actions?

Maybe simply disable/remove the built-in one (Eleven)? Do note that Eleven is capable of playing music directly from file managers, and Spotify may not have this function.