My Lenovo X1 Carbon has a touchscreen but I rarely use it. Sometimes on waking from suspend it generates spurious clicks that do things on my desktop like creating new folders. To disable the touchscreen completely, edit /etc/X11/xorg.conf.d/disable-touchscreen.conf as follows:

Section "InputClass"
    Identifier      "Annoying Touch Screen"
    Driver          "egalax"
    MatchProduct    "eGalax Inc. eGalaxTouch EXC7903-66v03_T1"

    Option          "DeviceEnabled" "0"

To work out the product name, use xinput:

$ xinput
⎡ Virtual core pointer                      id=2    [master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)]
⎜   ↳ eGalax Inc. eGalaxTouch EXC7903-66v03_T1  id=9    [slave  pointer  (2)]
⎜   ↳ SynPS/2 Synaptics TouchPad                id=12   [slave  pointer  (2)]
⎜   ↳ TPPS/2 IBM TrackPoint                     id=13   [slave  pointer  (2)]
⎣ Virtual core keyboard                     id=3    [master keyboard (2)]
    ↳ Virtual core XTEST keyboard               id=5    [slave  keyboard (3)]
    ↳ Power Button                              id=6    [slave  keyboard (3)]
    ↳ Video Bus                                 id=7    [slave  keyboard (3)]
    ↳ Sleep Button                              id=8    [slave  keyboard (3)]
    ↳ Integrated Camera                         id=10   [slave  keyboard (3)]
    ↳ AT Translated Set 2 keyboard              id=11   [slave  keyboard (3)]
    ↳ ThinkPad Extra Buttons                    id=14   [slave  keyboard (3)]

If you want to disable the touchscreen temporarily, instead of the Xorg tweak try this command:

xinput --set-prop 'eGalax Inc. eGalaxTouch EXC7903-66v03_T1' 'Device Enabled' 0

Thanks to Ian on the CLUG mailing list for help with the Xorg configuration.