Reset / Break Rehat or Centos root Password

 1:-just restart your system
 2:-press up down arrow 
 3:-press e
 4:-go to end of linux16 line 
 5:-jst give space and type rd.break enabled 0
 and remove that both words ( console=tty console=ttys0)
 6:-ctrl+x
 
 # mount -oremount,rw /sysroot
 #chroot /sysroot
 #passwd root
type new passwd:-redhat1234
retype same passwd:-redhat1234
 #touch /.autorelabel
 #exit
 #exit