Where is the horn fuse located?

Need to disable it.

That vehicle doesn't have an individual fuse for the horns. The horn gets power directly through the TIPM. The earliest build dates do have a removable horn relay, but that was relocated to the circuit board in the later build dates to make it non-replaceable.
The only other option would be to go to the horn sounder and unplug it to stop the horn.
Might I ask why you want to disable it?