To delete contents that you don’t want anymore for sure you can easily do so. Just mark the content/folder in the tree to the left and press the “Delete content”-button.
This will delete the content and it will not be possible to undo this operation later. You will have to confirm the action before it’s carried out. After you are done the tree will reload and you will now see that the item ha been deleted.
In later versions of InfoGlue you can also choose to delete all child contents to a folder. Very useful to clean a folder without having to break up relations to the folder. To use it just click the “Delete children”-button which is located below the normal delete-button (only available on folder-contents of course).