I have overhead fluorescent lights controlled by 2 switches, one by the door coming from the house and one by the door going to the outside on the side of the house. I bought a motion detector switch that is single pole (didn't notice until I got home) that I want to install to replace the first switch. In almost 5 years I have NEVER used the switch by the outside door. Can I install the single pole motion switch if I never turn off the other switch after installing? Any special wiring considerations? I'm not an experienced electrician (obviously), but I have replaced GFCIs, dimmers switches etc. I live in Maricopa county, AZ (city of Waddell) and am 65 with a college education in biology. Thanks for any help.

May or may not be possible.
Describe the wiring in each switch box.