To enable anonymous comments on your blog, follow these steps:
[1] go to your control panel by selecting Control Panel from the top menu.
[2] Select Manage 'XXX's' Blog
[3] Select Global Settings from the left hand menu
[4] Select Advanced Post Settings
[5] Change Allow Anonymous Users to Comment to yes
[6] Click 'Save'
You can also opt to moderate the anonymous comments - if you do, it is a good idea to set your email address in My Email Settings to get notified of comments otherwise they may sit there for a while.