How do I get iTunes to forget an iPhone?

I have three log-ins for my Mac (10.9.2): myself, my wife, and root. Months ago I was logged in to my wife's account to do some updates and stuff on my wife's iPhone, but I accidentally plugged my phone into the cable. It messed up my phone with her content, but it was fixable because everything was nicely backed up. But ever since then something annoying is happening: When I'm logged in to my wife's account and iTunes is open, iTunes mounts both my wife's iPhone and mine over the house wifi and tries to sync both. I quickly eject my phone, but I'd like iTunes to forget about my phone when logged in to my wife's account. (When logged in to my account, my wife's phone is not mounted.) In iTunes, the Devices Preference pane has the option to "prevent syncing automatically" enabled, yet syncing always starts nonetheless.

Anyone know how I can get my wife's iTunes to forget or ignore my phone?