Is it possible to remember a network but manually initiate connection every time? I occasionally use my phone to connect to the work network for quick diagnostic purposes. I do not like being connected to it for regular use, as I don't like my phone activity to be traceable by my employer.

Is it possible to remember a WiFi network, but only connect when manually triggered?
This is not possible, but as Matt said, the best thing to do is just to turn off your Wi-Fi. There are apps that you can download that will be able to automatically turn off Wi-Fi at your workplace. However, I personally keep my Wi-Fi off at all times, regardless of whether or not I am home. Wi-Fi, despite what most battery saving apps will tell you, consumes more power than cellular when you are not using it heavily. For streaming and updating apps, I connect to Wi-Fi, but that is about it.