The manual for this camera can be freely viewed, downloaded and printed - here
. You may want to review the manual first to refresh your memory of the camera's operation and functions.
To your question - page 18 describes using the trash can icon to delete the current image (the one being displayed) and page 41 details deleting unprotected pictures. Page 65 details how to remove protection from pictures so that they may be deleted.
I hope this helps & good luck!