Primoz is right. When you disable 5G radio on MESH AP. It goes offline and disconnected from ZD and Root or upstream mesh AP if any. Post disabling 5G radio on MESH if you have to enable 5G back there is NO way to enable 5G on disconnected MESH AP as Mesh is OFF and this AP is nolonger in control of ZD hence it is stranded. On dual band AP's mesh won't happen on 2.4g on a side note.
On your question - how to disable the production WLANs, and how to disable the mesh WLAN.
There is NO option to disable Mesh WLAN on ZD except hard reset. You can only turn off mesh on connected AP on ZD as seen in the image you posted - https://d2r1vs3d9006ap.cloudfront.net...
As far as disabling production WLANs is concerned, you make a WLAN group with NO SSID or WLAN in it.
Then you can make a AP group include the AP model (example ZF7782) and then assign the WLAN group you created above to this AP group. this will apply to all Zf7782 AP's
hope this helps.