Hi!

This has been covered in hundred different tutorials and many more threads and you do not ven have to search for it. Just go to the Tutorials forum and you will find several faction tutorials in one minute.
So, please, look there, as posting it again and again is really annoying.

For the removing part: Why would you remove a faction completely? If your mod should be playable in SP (with story) I would not do this anyway, as many factions are involved in the story and it could be screwed up, if you delete one. If it is an MP mod this is not a problem, but it is not necessary to delete one.

So, my suggestion: You want to create a new faction and you want to get rid of one. Why not change the one you do not need anymore, so that it is your new one (just change the names, the ships they fly, bases they own, etc.). This would be the easiest way to do it and you did not even need to create new entries, but just change the old ones.

Black Eagle