Welcome to the forum! 
That’s because you somehow did not let the update finish. Maybe the connection was lost, or maybe you rebooted the machine in the middle of the update. The update process first removes the kernels and then installs the newer ones.
Boot up from the live medium and open up a terminal window. Then issue the command… 
su -
Next, issue the following command…
manjaro-chroot -a
It will try to detect the root filesystem of the installed Manjaro system, and if it finds more than one distribution, it’ll let you choose the correct partition.
Then, you select the correct one, and you issue the command…
pacman-mirrors -f 5 && pacman -Syyu
This will resume or restart the update process. Be sure to let it finish this time, and when you’re done, issue the following two commands…
exit
systemctl reboot
That should fix it. 