Slide the little red tab out carefully with a small screwdriver, I usually take it out completely so I don't lose it, then press the release and slide them apart. Unfortunately the dry desert heat here is really hard on plastic so its still 50/50 if they'll break. Adding a little dielectric grease (I use SuperLube) will help them go back together easier and might help them come apart again later. I just replaced my oil pressure sender and luckily didn't break the connector.