After seeing some of the "Mech Warrior" type ship designs, and the "Home World" one - well done to u lot for being so good at designing ships (especially those who then put them up for download)
I have gotten back into ship design.... Which I actually started to find a bit boring... You can only ever really manage either a lightly armed ship with good armour or a lightly armoured ship with good attack, but not both (that is if you don't cheat and make your miniaturization skill something like a couple of million or something stupid).
What I would like people to do, if they are going to put their ship designs up, is to right a proper readme file - half the ones I downloaded don't work! This is people just say stick it in this folder, and there is always two or three of this folder, in two or three different places... Then theres the other files, which go where?
Oh well...
With regards to the core ships.... I don't think you can delete it..... All you can try is to either open the file in Notepad (or look up the Cooktop editor, which is an .xml editor and is free to download) - file being GC2ships.xml
Highlight the details of 1 ship, e.g. the constructor, CUT IT (don't delete it whatever you do), save the file but DO NOT close it, then run the game - START a new game, as a loaded one will not recognise the new data - I've tried this with the tech tree, which is why I say this.
If the game doesn't like it, then you can just maximise notepad and paste it back, resave it, and then you'll know!
Hope this helps!