Move /home logical volume to /, lvremove, lvextend, lvs

# move to home
cd

# umount home
umount /home

# remount to /mnt
mount /dev/mapper/centos-home /mnt

# go to /mnt
cd /mnt

# move everything to default /home
mv * /home

# delete /home mount point from fstab
vi /etc/fstab

# check situation
vgdisplay

# it will report
# Free  PE / Size       0 / 0

# check all volume groups
lvs

# check if you are on the right machine
hostname

# delete volume group
lvremove /dev/mapper/centos-home

# check if the vg disappears
lvs

# check situations
vgdisplay
#   Free  PE / Size       6911 / <27.00 GiB

# extend group with one gigabyte
lvextend -L+1G /dev/mapper/centos-root

# use all available space
lvextend -l +100%FREE /dev/mapper/centos-root

# check again
vgdisplay