In my opinion, the best way to deal with moderators like that is to demote them. I unfortunately know this from experience - they're going to abuse their power, a lot. It's best to deal with the situation now before it turns into a bigger problem.
Personally i'd create a new usergroup, something more generic like "Staff" , give it most moderation permissions, like normal moderators would have, edit, move, rename, etc...add them to this new group and tell them you're re-structuring the permissions and staff structure to better serve your users and the site in general. If they're unwilling to accept the new structure, make them an ex-staff usergroup and add the ones who want to step down on there, thanking them for their service, with perhaps some perks normal users would not have.
I was acutally in and out of the hospital the past weeks following a surgery that went wrong! I stayed to my guns and told them I respected their input in policy changes -- but that I was pushing them public. One stepped down and other is still bitterly there. But it's a lot less tension once I told them 'this is the policy and you can agree to it or not -- your choice'.
Worst part in some of such forums is that moderators chase you when you express opinion. let's assume you have right wing opinion and moderator is left wing. he will chase you till you get annoyed and attack him back and then he can lift the ban hammer. I hate when that happens. I like facebook for this reason, which in past forums were holding authority, now with facebook groups and all, you can quit discussion when left wing folks trap you into PC argument.
1. Safety first: all accounts set to moderation, with moving / sending to moderation privileges only. YOU as the admin are the ONLY one to have access to general administration, delete stuff, anything that can be irreplaceable.
2. Create a thread in which to public thank the current mod team for their outstanding contribution and keeping the forums alive. Get them some cool badges or something, they are clearly vane about this. It doesn't hurt to praise them a little.
3. in the mod forum (if you have one), thank them again and discuss your plans to further develop the community. See who's willing to help along, who's not, should remain with those super hero badges and that's it.
If they become aggressive or don't abide by the rules, kindly explain the guidelines (if you have none, put some in place) and remove them from the comnunity, if needed. Keep on posting content and engaging users throughout this stage, so the community is still active and thriving.