Is there a way to remove the link on full size images in posts/pages?
I still would like to have it for the other smaller sizes. Since the full size image is already full size, it seems unnecessary to link to itself.
If you're adding the full size image from the Post Editor, when you select the image from the media manager pop-up box, you'll click the button that says "None" under the Link URL field.
That would be impossibly messy to control programatically. Well, maybe not impossible, but probably something that you would just hack with jQuery or something. (Find all full size images and remove the A tag sort of thing.)
Go to /wp-admin/options.php. This will give you the master list of all options. Note that it is not wise to modify things on this page, you can easily break stuff here.
Scroll down until you find the "image_default_link_type" option. It may be empty.
Valid values here are "none", "file", and "post".
Set it to "none" to have the default link for new image insertions be blank.
After you enter the new value, you can go down to the Save button, or simply press enter to save the value.
Again, it is not recommended to change setting values via this screen, but there is no other method by which to modify this internal option.