... and click the (Remove) link near the bottom right of the post.
At the end of each of your journal entries it should have the following information:
[font style="color:#999999; font-size:0.85em;"]Posted by fadedrose | [/font][font style="color:#0000cc; font-size:0.85em;"]day date, time (# replies)[/font]
The second half of that is a link that will take you to the post where you can click the (Remove) link. By default, your posts will open in the same window/tab - it will probably go quicker if you open the posts up in a new tab/window by right-clicking the links and selecting that option.
It looks like you have quite a few pages, so it might take quite a bit of time to go back and remove all of them. As far as saving space on DU's servers, the odds are pretty good that journal entries are simply pointers back to your posts - which means deleting your entries will save almost no space at all. I'd only recommend taking the time to delete entries if you actually don't want them in your journal - for instance if you plan to start using your journal to collect selected posts of particular interest and want to remove the less important ones.