Sounds like they are read only or another setting and you need to change the attibutes to delete them.
Run this query in SQL MS, this will tell you the attribute number.
Select * from item
where guid = 'insertpackageguid'
Run this statement to change the attibutes, then you should be able to see delete in the context menu.
UPDATE Item SET Attributes = 0
WHERE Guid = 'insertpackageguid'
Let us know.