If you want publishing dissabled, I would just stop publishers service. No need to remove targets and other stuf. You can even push notifications about maintenace. You can check how to achieve this by looking into Atila's Sos last year Tridion Developers Summit lightning talk
As Marko mentioned, if you want to suspend publishing altogether, you could just stop all Publisher Services.
If you are using Topology Manager, you can also mark individual CD Environments as "offline". This will suspend publishing to those CD Environments only.
Maybe a reason to migrate to Topology Manager based publishing? :-)