The only thing you can do to free up space in /boot is to remove kernels. You can figure out how may you have by simply listing the files and counting the number of vmlinuz* files there. A 487 MB boot partition is really small. In /etc/yum.conf you can set "installonly_limit=#" (where # is a number) and that will limit you to only # kernels and any more than that will be removed when a new one is installed. You need at least 2, so you can go back to an older kernel if you have issues. You can also use "package-cleanup --oldkernels --count=#" to manually reduce the number of kernels to #. You'll want to search/read up on "limit number of kernels CentOS" or something like that to get more details etc.
The root partition ("/") is where everything else is stored. The rest of the OS, all your sites/email, MySQL is stored there. Unless you have very large error_log files the only way to clean up space to to reduce the account usage.
You basically have a very small system.
If you mean in /Boot
All files are those :
total 411824
dr-xr-xr-x. 6 root root 4096 Mar 4 03:31 .
drwxr-xr-x 20 root root 4096 Mar 18 00:10 ..
-rw-r--r-- 1 root root 153567 Aug 25 2020 config-3.10.0-1127.19.1.el7.x86_64
-rw-r--r-- 1 root root 153596 Dec 18 2020 config-3.10.0-1160.11.1.el7.x86_64
-rw-r--r-- 1 root root 153596 Jun 10 2021 config-3.10.0-1160.31.1.el7.x86_64
-rw-r--r-- 1 root root 153595 Nov 17 2020 config-3.10.0-1160.6.1.el7.x86_64
-rw-r--r-- 1 root root 153619 Jan 25 20:45 config-3.10.0-1160.83.1.el7.x86_64
drwxr-xr-x. 3 root root 1024 Sep 18 2017 efi
drwxr-xr-x. 2 root root 1024 Dec 9 2020 grub
drwx------. 5 root root 1024 Feb 22 00:31 grub2
-rw-------. 1 root root 51313370 Sep 18 2017 initramfs-0-rescue-9063ac396d784f4c997ceacdd0590c25.img
-rw------- 1 root root 52462335 Jun 12 2021 initramfs-3.10.0-1127.19.1.el7.x86_64.img
-rw------- 1 root root 13756102 Jun 12 2021 initramfs-3.10.0-1127.19.1.el7.x86_64kdump.img
-rw------- 1 root root 53847637 Nov 11 05:04 initramfs-3.10.0-1160.11.1.el7.x86_64.img
-rw------- 1 root root 13757946 Jun 17 2021 initramfs-3.10.0-1160.11.1.el7.x86_64kdump.img
-rw------- 1 root root 53850884 Nov 11 05:03 initramfs-3.10.0-1160.31.1.el7.x86_64.img
-rw------- 1 root root 52465237 Jun 12 2021 initramfs-3.10.0-1160.6.1.el7.x86_64.img
-rw------- 1 root root 54257895 Feb 22 00:31 initramfs-3.10.0-1160.83.1.el7.x86_64.img
-rw------- 1 root root 13800046 Mar 4 03:31 initramfs-3.10.0-1160.83.1.el7.x86_64kdump.img
drwx------ 2 root root 12288 Dec 9 2020 lost+found
-rw-r--r-- 1 root root 320536 Aug 25 2020 symvers-3.10.0-1127.19.1.el7.x86_64.gz
-rw-r--r-- 1 root root 320678 Dec 18 2020 symvers-3.10.0-1160.11.1.el7.x86_64.gz
-rw-r--r-- 1 root root 320759 Jun 10 2021 symvers-3.10.0-1160.31.1.el7.x86_64.gz
-rw-r--r-- 1 root root 320667 Nov 17 2020 symvers-3.10.0-1160.6.1.el7.x86_64.gz
-rw-r--r-- 1 root root 320743 Jan 25 20:46 symvers-3.10.0-1160.83.1.el7.x86_64.gz
-rw------- 1 root root 3612420 Aug 25 2020 System.map-3.10.0-1127.19.1.el7.x86_64
-rw------- 1 root root 3617106 Dec 18 2020 System.map-3.10.0-1160.11.1.el7.x86_64
-rw------- 1 root root 3620234 Jun 10 2021 System.map-3.10.0-1160.31.1.el7.x86_64
-rw------- 1 root root 3617083 Nov 17 2020 System.map-3.10.0-1160.6.1.el7.x86_64
-rw------- 1 root root 3623845 Jan 25 20:45 System.map-3.10.0-1160.83.1.el7.x86_64
-rwxr-xr-x. 1 root root 5877760 Sep 18 2017 vmlinuz-0-rescue-9063ac396d784f4c997ceacdd0590c25
-rwxr-xr-x 1 root root 6765160 Aug 25 2020 vmlinuz-3.10.0-1127.19.1.el7.x86_64
-rw-r--r-- 1 root root 172 Aug 25 2020 .vmlinuz-3.10.0-1127.19.1.el7.x86_64.hmac
-rwxr-xr-x 1 root root 6769256 Dec 18 2020 vmlinuz-3.10.0-1160.11.1.el7.x86_64
-rw-r--r-- 1 root root 172 Dec 18 2020 .vmlinuz-3.10.0-1160.11.1.el7.x86_64.hmac
-rwxr-xr-x 1 root root 6773352 Jun 10 2021 vmlinuz-3.10.0-1160.31.1.el7.x86_64
-rw-r--r-- 1 root root 172 Jun 10 2021 .vmlinuz-3.10.0-1160.31.1.el7.x86_64.hmac
-rwxr-xr-x 1 root root 6769256 Nov 17 2020 vmlinuz-3.10.0-1160.6.1.el7.x86_64
-rw-r--r-- 1 root root 171 Nov 17 2020 .vmlinuz-3.10.0-1160.6.1.el7.x86_64.hmac
-rwxr-xr-x 1 root root 7051880 Jan 25 20:45 vmlinuz-3.10.0-1160.83.1.el7.x86_64
-rw-r--r-- 1 root root 172 Jan 25 20:45 .vmlinuz-3.10.0-1160.83.1.el7.x86_64.hmac
There is only 11 vmlinuz , which one should i remove ?
* About "installonly_limit=#" , currently it is set to 5 , is it enough ?!
* Also "package-cleanup --oldkernels --count=#" , should it be set to 5 in my case or it doesn't matter to the previous number of ( installonly_limit ) .
* The root partition , it is almost 500 GB of size , i think it could be the Backup files which is taking more space , what command can alow me view the large files / folders ?