The door position switch is an internal part inside the door latch mechanism. There is no fuse to shut it up, the body control module is sending that to the digital dash readout and the warning klaxon is universal to all of the dashboard gauges and failures. The fuse that would shut it up would also disable the vehicle. If this is the drivers door, there's also the possibility that one of the wires in the door bundle boot has failed, the door panel must be removed to check the switch.
Sorry there is no easy fix. If this is the power tailgate latch, try spraying some white lithium grease in the Cadillac trunk lid style power capture motorized latch assembly, the one on my 2008 Suburban has issues at times and some spray can white lithium grease always gets it working again. Most of my power lift-gate issues are in the winter with the power latch mechanism icing up, where I then have to thaw it with a hair drier to get it to close properly.
Once you remove the door panel and peal the moisture shield back, you should be able to get your hand in there to disconnect the door latch wire connector and short it with a paper clip to determine if the door latch switch is good or if the wire boot bundle back to the body control module is bad as the door should show closed when you short the door latch position 2 wire connector. If shorting that connector shuts it up, you can leave it bypassed. At that point you are only a few screws away from replacing the latch if it's bad.