I just did an update that installed a new kernel. All the old kernel files were deleted from /boot except for the dtb directory. In this case, dtb-4.14.82-201.el7.armv7hl
Here is a list of the /boot directory. What is needed to make sure everything old is removed from boot?
$ ls -ls /boot/ total 292730 2 -rw-r--r--. 1 root root 2 Nov 3 2018 boot.scr 204 -rw-r--r--. 1 root root 206130 Jun 17 20:53 config-4.14.127-200.el7.armv7hl 204 -rw-r--r--. 1 root root 206070 Jan 6 09:38 config-4.14.91-201.el7.armv7hl 27 drwxr-xr-x. 2 root root 25600 Jun 23 09:19 dtb-4.14.127-200.el7.armv7hl 27 drwxr-xr-x. 3 root root 25600 Jun 23 09:23 dtb-4.14.82-201.el7.armv7hl 27 drwxr-xr-x. 2 root root 25600 Jan 11 14:44 dtb-4.14.91-201.el7.armv7hl 2 drwxr-xr-x. 2 root root 1024 Jun 23 09:29 extlinux 2 drwxr-xr-x. 2 root root 1024 Dec 5 2016 grub 34835 -rw-------. 1 root root 35529320 Dec 5 2016 initramfs-0-rescue-e3a7bc0f423e4311a45e7d423cb8743d.img 42323 -rw-------. 1 root root 43166836 Jun 23 09:29 initramfs-4.14.127-200.el7.armv7hl.img 42243 -rw-------. 1 root root 43085027 Jan 11 14:52 initramfs-4.14.91-201.el7.armv7hl.img 597 -rw-r--r--. 1 root root 605252 Dec 5 2016 initrd-plymouth.img 2 -rw-------. 1 root root 49 Jun 23 09:29 klist.txt 13 drwx------. 2 root root 12288 Dec 5 2016 lost+found 3374 -rw-------. 1 root root 3438384 Jun 17 20:53 System.map-4.14.127-200.el7.armv7hl 3370 -rw-------. 1 root root 3434223 Jan 6 09:38 System.map-4.14.91-201.el7.armv7hl 6537 -rw-r--r--. 1 root root 6664768 Jun 23 09:29 uImage 6537 -rw-r--r--. 1 root root 6664768 Jun 23 09:29 uImage-4.14.127-200.el7.armv7hl 6521 -rw-r--r--. 1 root root 6648384 Jan 11 14:52 uImage-4.14.91-201.el7.armv7hl 42323 -rw-r--r--. 1 root root 43166900 Jun 23 09:29 uInitrd 42323 -rw-r--r--. 1 root root 43166900 Jun 23 09:29 uInitrd-4.14.127-200.el7.armv7hl 42243 -rw-r--r--. 1 root root 43085091 Jan 11 14:52 uInitrd-4.14.91-201.el7.armv7hl 5936 -rwxr-xr-x. 1 root root 6051744 Dec 5 2016 vmlinuz-0-rescue-e3a7bc0f423e4311a45e7d423cb8743d 6537 -rwxr-xr-x. 1 root root 6664704 Jun 17 20:53 vmlinuz-4.14.127-200.el7.armv7hl 6521 -rwxr-xr-x. 1 root root 6648320 Jan 6 09:38 vmlinuz-4.14.91-201.el7.armv7hl