xinput list
Get name of device, get properties
xinput list-props "Logitech Unifying Device. Wireless PID:101a"
Get name of accel profile property, set it
xinput set-prop "Logitech Unifying Device. Wireless PID:101a" "Device Accel Profile" -1
Add to .bashrc or whatever
Alternatively, if the mouse is annoying and has duplicate names for some reason (G502):
xinput list | grep "Logitech Gaming Mouse G502" | grep -P '\d+(?=\s+\[)' -o | xargs -n1 -I id xinput set-prop id 277 -1
Can also turn it off via xorg conf:
$ cat 50-mouse-acceleration.conf
Section "InputClass"
Identifier "Mouse0"
MatchIsPointer "yes"
Option "AccelerationProfile" "-1"
EndSection