Remove Public Folder Replication in a DAG

You must not remove the folder, but you need to remove the replicas from srv2, provided everything is replicated to srv1. Check which PF's are hosted only on srv2 (using its DB name):
Get-PublicFolder -Recurse | Where {$_.Replicas -eq 'SRV2 DB'} | Select Name, ParentPath, Replicas
To move all replicas hosted on srv2 to srv1, you can use a standard provided script, located in $exscripts\Scripts, e.g.
.\MoveAllReplicas.ps1 -Server srv2 -NewServer srv1
Wait until all replicas have been succesfull moved to srv1. After that, you can remove the public folder DB from srv2, after you have done some checks, such as checking if all mailbox databases are pointing to the PF database on srv1:
Get-MailboxDatabase | select Name, publicFolderDatabase
OAB generation is performed by srv1:
Get-OfflineAddressBook -Identity 'Default Offline Address Book'