Can I leave condenser mic out?
Leaving a condenser mic such as this Rode NT1A on it's stand and powered up when not in use does no damage, though you might want to keep the dust off with a polythene bag. ... So leaving a mic powered is unlikely to shorten its life significantly, and may well actually prolong it.
How do I disconnect my microphone?
Use the Device Manager
Right-click on the Start Button and open Device Manager. In the Device Manager window, expand the Audio inputs and outputs section and you will see your Microphone listed there as one of the interfaces. Right click on Microphone and select Disable.