CentOS 7: Single User Mode

  Linux

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.

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

Used this – https://www.unixmen.com/reset-root-password-centos-7/