Guild Question for ZOS please...

big_ear_midget

We have a guild that is yellow (aldemeri dominion) and we are thinking of changing it to red (ebonheart pact). My question is, do we have to delete the guild and remake or can ZOS change this for us? If we have to delete the guild, can we reuse the same name or will that name be unavailable for us to use again? Thanks in advance!