Need Wiring Help to Install Overhead Light Garage Sensor
We recently bought a home which was built in 2007 and has five overhead garage fluorescent fixtures. Trying to install an occupancy sensor to turn lights on when vehicles enter the garage. Since I plan to have a shop in the garage at a later date, I purchased an occupancy sensor which also has an on-off switch to enable me to switch the lights on for long periods of time. It is a Cooper Wiring OS310U Auto On Sensor (Single Output) which works as single pole and 3-way, and it works with fluorescent fixtures.
A contractor set up the wiring for this new sensor switch, but he's gone and I can't reach him. He left one 3-way switch which we won't need. This unneeded switch has 3 White tied, 3 Ground tied, 1 Red wire, and 3 Black wires tied. The Red wire is tied to the 3-way switch and the 3 Black wires are tied and have 1 Black leading to the 3-Way switch. My assumption is that I need to connect the two wires (1 Black and 1 Red) which now connect to the 3-way switch so that it will be always-ON, then cover these wires and wire nuts with a blank plate.
I'll attach a file which shows the existing wiring in the desired occupancy sensor 3-way switch location. It has 4 wires: 2 Black, 1 White, and 1 Ground.
Should I use a voltage tester to determine which is the hot black wire at the new occupancy sensor location? If this is the case, then the wiring diagram from Cooper Wiring shows the switch's wiring connections for a switch in one location, and I can make all of the connections. Just didn't want to blow up a new switch, and very much appreciate your guidance.