Did you hear of room lists? What is a room list?
A room list is a collection of room mailboxes. Room lists are specially marked distribution groups that you can also use the same way you use ‘regul...
Updated May 21, 2020
Version 5.0
Blog Post
Mats1349
My guess is you have at least one (maybe multiple) meeting room resources which have the City or Building property configured with that city name. The rooms probably don't belong to a room list - either that, or they may belong to a room list which is hidden from the GAL.
I suggest running the following in Powershell, then searching the output for the city you're trying to get rid of.
Get-Mailbox -RecipientTypeDetails RoomMailbox -ResultSize Unlimited | Get-Place | Export-CSV c:\filepathgoeshere\output.csv
Alternatively if you're more fluent in Powershell than me, you could modify it to only return rooms where the City or Building property matches a particular value.
Good luck!