Captivate and gmail address

I'm quite familiar with computers,  however these smart phones have a new learning curve about them.

I bought 2 Captivates 5 days ago and I am trying to learn the ins and outs.  I bought them at Costco and they were very helpful, and transferred our phone directories from Verizon with out a hitch,  everything came through perfectly.  But, the tech guy reversed the 2 gmail accounts between my phone and my wife's phone.  I have since added my gmail to my phone and her gmail to her phone, but if I try to delete the unnecessary gmail account,  a message appears that says the phone will be set back to factory defaults.

I assume this will erase what I have established in the devices, downloaded apps, and  especially our phone directories and maybe other things I am not aware of at this point.  Is there any way around this to eliminate the wrong gmail on both our phones.

Thanks in advance for any input.

Bill