changing server from 1.9.2 to 1.8.8

so i just downloaded everything to make a server on CentOs or linux and i noticed that it was 1.9.2 and i wanted to change it to 1.8.8 from 1.9.2. i changed the BuildTools.log to 1.8.8 and all but i dont know how to make it all update to it. please help.