If you're playing the games in Steam, using Steam Input, there's an option to disable it.
Steam->Settings->Controller->Game rumble
A number of games will also have an option to do so.
EDIT: If you are certain that you don't ever want rumble, you could probably open up the controller and just disconnect one of the wires running to each motor. I think that the XBox controllers use security bits, though. I had to open one a while back.
kagis
Yeah:
https://www.ifixit.com/Wiki/Xbox_Controller_Screwdriver
A TR8 Torx Security screwdriver can remove the fasteners securing Xbox 360 controllers and standard Xbox One and Xbox Series X|S controllers.
Note that the security Torx bits aren't regular Torx bits, so if you do want to do that, be sure to get the security bit.
Could even just remove the motors from the controller, make it a bit lighter.
EDIT2: I think that the controller uses the xpad driver (if it does, it should be loaded and visible when you run lsmod and have the game controller active). Unfortunately, that doesn't seem to have an option to disable force feedback at the driver level:
$ modinfo -p xpad
dpad_to_buttons:Map D-PAD to buttons rather than axes for unknown pads (bool)
triggers_to_buttons:Map triggers to buttons rather than axes for unknown pads (bool)
sticks_to_null:Do not map sticks at all for unknown pads (bool)
auto_poweroff:Power off wireless controllers on suspend (bool)
$
There are some software packages that let you create "virtual" controllers that take input from another controller. That adds more moving parts, but if none of the above options work for you, you could look into that.