It seems that you want to know how to delete the orphaned namespace information \\ourdomain.tld\DFS_Test from the DFS Management console. Meanwhile, you can query the current namespace \\ourdomain.tld\DFS_Prod which is on the production server.
As the domain-based DFS configuration stores in the AD database, every time we launch the DFS management console, it will try to retrieve the DFS information from AD.
There are two nodes in AD which stores the information of the DFS:
Node1. Store the DFS Namespace information which shows under the Namespaces node in DFS management console.
CN=DFS-Configuration, CN=System, DC=Domainname, DC=domainsuffix
Node2. Store the DFS Replication group information which shows under the Replication node in DFS management console.
CN=DFSR-GlobalSettings, CN= System, DC=Domainname, DC=domainsuffix
In this case, you may use ADSIedit.msc to delete the orphaned namespace information \\ourdomain.tld\DFS_Test under the node CN=DFS-Configuration.
1. Launch ADSIedit.msc
2. Connect to „Default naming context“ (the domain partition)
3. Expand and locate to the following node:
CN=Dfs-Configuration, CN=System, DC=ourdomain, DC=tld
4. Check if the orphaned namespace CN=DFS_Test is under it, if so, you may delete this node CN=DFS_Test
Afterwards, please run „repadmin /syncall“ if there is multiple domain controllers in the environment and then run „dfsrdiag pollad“ on all the DFS member servers to manually make them sync the information from AD database.
Then, you may launch the DFS management console and then right-click on the orphaned namespace, and then select Remove Namespace from Display… if needed.