wondering if I can delete what I think are old kernel images

Question

I have extremely low space in /boot and wondering I could get rid if a few things. This is the output of sudo ls -al /boot:

total 216002  
drwxr-xr-x  4 root root     3072 Feb 20 12:33 .  
drwxr-xr-x 23 root root     4096 Feb 20 12:30 ..  
-rw-r--r--  1 root root  1271689 Oct 22  2015 abi-3.19.0-32-generic  
-rw-r--r--  1 root root  1239577 Apr 18  2016 abi-4.4.0-21-generic  
-rw-r--r--  1 root root  1244118 Jan  6 17:44 abi-4.4.0-59-generic  
-rw-r--r--  1 root root  1244118 Jan 18 08:59 abi-4.4.0-62-generic  
-rw-r--r--  1 root root  1245512 Feb  1 12:39 abi-4.4.0-63-generic  
-rw-r--r--  1 root root   177790 Oct 22  2015 config-3.19.0-32-generic  
-rw-r--r--  1 root root   189412 Apr 18  2016 config-4.4.0-21-generic  
-rw-r--r--  1 root root   190047 Jan  6 17:44 config-4.4.0-59-generic  
-rw-r--r--  1 root root   190047 Jan 18 08:59 config-4.4.0-62-generic  
-rw-r--r--  1 root root   190247 Feb  1 12:39 config-4.4.0-63-generic  
drwxr-xr-x  5 root root     1024 Feb  2 19:56 grub  
-rw-r--r--  1 root root 35945618 Jan 15 04:42 initrd.img-3.19.0-32-generic  
-rw-r--r--  1 root root 40519001 Jan 15 08:48 initrd.img-4.4.0-21-generic  
-rw-r--r--  1 root root 41067223 Feb  2 09:45 initrd.img-4.4.0-59-generic  
-rw-r--r--  1 root root 41069127 Feb  2 19:56 initrd.img-4.4.0-62-generic  
drwx------  2 root root    12288 Jul  6  2016 lost+found  
-rw-r--r--  1 root root   182704 Jan 28  2016 memtest86+.bin  
-rw-r--r--  1 root root   184380 Jan 28  2016 memtest86+.elf  
-rw-r--r--  1 root root   184840 Jan 28  2016 memtest86+_multiboot.bin  
-rw-------  1 root root  3628149 Oct 22  2015 System.map-3.19.0-32-generic  
-rw-------  1 root root  3853719 Apr 18  2016 System.map-4.4.0-21-generic  
-rw-------  1 root root  3875594 Jan  6 17:44 System.map-4.4.0-59-generic  
-rw-------  1 root root  3875553 Jan 18 08:59 System.map-4.4.0-62-generic  
-rw-------  1 root root  3883990 Feb  1 12:39 System.map-4.4.0-63-generic  
-rw-r--r--  1 root root  6572944 Jul  4  2016 vmlinuz-3.19.0-32-generic  
-rw-------  1 root root  7013968 Apr 18  2016 vmlinuz-4.4.0-21-generic  
-rw-------  1 root root  7069136 Jan  6 17:44 vmlinuz-4.4.0-59-generic  
-rw-------  1 root root  7070992 Jan 18 08:59 vmlinuz-4.4.0-62-generic  
-rw-------  1 root root  7087088 Feb  1 12:39 vmlinuz-4.4.0-63-generic  

If I am correct I could delete everything with lower numbers before generic.

Example:

vmlinuz-4.4.0-21-generic
vmlinuz-4.4.0-59-generic
vmlinuz-4.4.0-62-generic
vmlinuz-4.4.0-63-generic

I should be able to delete:

vmlinuz-4.4.0-21-generic
vmlinuz-4.4.0-59-generic
vmlinuz-4.4.0-62-generic

Please tell me if I am able to do this to clear space without damaging my system.

Answer 1

On Debian-based distributions (which Linux Mint is since Ubuntu is), sudo apt-get autoremove will remove any old kernels (and possibly other packages) that you no longer need. This is recommended rather than deleting the files manually.

Answer 2

If you are running 4.4.0-63, you can delete all the vlinuz-*, System.map-*, initrd.img-*, config-*, abi-*, except those containing the string 4.4.0-63. However, for resilience , I would keep the previous version around i.e. those files containing 4.4.0-62.

You may have to update GRUB or whatever bootloader you use afterwords.