Deleting/removing artifacts and content requires two steps.
First, you need to remove it from use in the ePortfolio sections.
Second, you can then delete it from your ePortfolio Library.
Here are documents of how to do that:
ePortfolio section artifact removal: http://chalkandwire.mindtouch.us/1Co...diting_Content
Artifact deletion from Library: http://chalkandwire.mindtouch.us/Art...lete_Artifacts
Please let me know if these steps will not work for you.
Things to be aware of ...