In the boot grub menu select option to edit.

Select Option to edit (e).

Go to the line of Linux 16 and change ro with rw init=/sysroot/bin/sh.

Now press Control+x to start on single user mode

Now access the system with this command ( chroot /sysroot )

Reset the password ( passwd root )

Update selinux information ( touch /.autorelabel )

Exit chroot ( exit )

Reboot your system ( reboot )