wavy hair to straight hair

Okay i naturally have wavy curly hair a little straight but its not nappy or kinky. but i dont use wave grease i stopped using vaseline when i used to it would wave up more so now i use pink oil or a leavin conditioner but it just waves or curles up my hair is short you know its not a fro or a mini fro or a bob. but how can i make it straight like after i wash it it waves up when i brush it while its a lil damp without any greases or oils in it. wut do i do to keep it or make it straight its the length of the men on the boxes of the s-curl kits (so its not a fro or bob)