[Samba] Why Can I Delete?

[Michael Stearne]

If user1 creates a file on the share, why with this configuration can
user2 delete that file created by user1?

Thanks,
Michael

[global]
	idmap gid = 16777216-33554431
	idmap uid = 16777216-33554431
	path = /var/www/
	unix password sync = yes
	workgroup = cmny
	os level = 20
	auto services = advertising editorial
	null passwords = yes
	encrypt passwords = yes
	winbind use default domain = no
	security = user
	template shell = /bin/false
	lock directory = /var/lock/smb
	share modes = yes
	locking = yes

[advertising]
	wide links = no
	path = /var/www/advertising
	strict locking = yes
	valid users = @advertising
        oplocks = False
        level2 oplocks = False
        public = no
        writable = yes
        create mask = 0700
        force create mode = 0700
        directory mask = 0700
        force directory mode = 0700