/dev/mapper/centos-root is 99% how can i solve this problem

hi all Filesystem Size Used Avail Use% Mounted on devtmpfs 24G 0 24G 0% /dev tmpfs 24G 1.9M 24G 1% /dev/shm tmpfs 24G 644M 23G 3% /run tmpfs 24G 0 24G 0% /sys/fs/cgroup /dev/mapper/centos-root 50G 49G 1.4G 98% / /dev/sda1 1014M 233M 782M 23% /boot /dev/sdb 1.1T 560G 485G 54% /backup /dev/mapper/centos-home 873G 170G 703G 20% /home tmpfs 4.7G 12K 4.7G 1% /run/user/42 tmpfs 4.7G 40K 4.7G 1% /run/user/0 tmpfs 4.7G 0 4.7G 0% /run/user/1003 how can i solve this problem any help plz