Can i delete system default groups which does not have any users or are of no use?

Issue

• can i delete the groups below, also provide the usage of each group.

• dip     • floppy     • games     • kmem     • lock    
• man     • mem        • slocate   • tty      • utmp        

• can i change permissions of unused service directories?Both samba & isdn services are disabled in chkconfig.

drwxrwxrwt  2 root root 4096 Dec 22  2005 /var/spool/samba/
drwxrwxrwt  2 root root 4096 Oct  5  2004 /var/spool/vbox/