For Ubuntu 19.04
In addition to Nolf's answer, you can also set these settings on the command line with these commands:
gsettings set org.gnome.shell.extensions.dash-to-dock hot-keys false
gsettings set org.gnome.shell.keybindings switch-to-application-1 []
gsettings set org.gnome.shell.keybindings switch-to-application-2 []
gsettings set org.gnome.shell.keybindings switch-to-application-3 []
gsettings set org.gnome.shell.keybindings switch-to-application-4 []
gsettings set org.gnome.shell.keybindings switch-to-application-5 []
gsettings set org.gnome.shell.keybindings switch-to-application-6 []
gsettings set org.gnome.shell.keybindings switch-to-application-7 []
gsettings set org.gnome.shell.keybindings switch-to-application-8 []
gsettings set org.gnome.shell.keybindings switch-to-application-9 []
Update:
I'm using Dash to Panel now (instead of Dash to Dock) and got the same problem back again. Now we need these commands:
dconf write /org/gnome/shell/extensions/dash-to-panel/hot-keys false
dconf write /org/gnome/shell/extensions/dash-to-panel/hotkey-prefix-text "''"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-1 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-2 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-3 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-4 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-5 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-6 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-7 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-8 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-9 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-10 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-kp-1 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-kp-2 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-kp-3 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-kp-4 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-kp-5 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-kp-6 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-kp-7 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-kp-8 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-kp-9 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-hotkey-kp-10 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-1 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-2 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-3 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-4 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-5 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-6 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-7 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-8 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-9 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-10 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-kp-1 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-kp-2 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-kp-3 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-kp-4 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-kp-5 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-kp-6 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-kp-7 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-kp-8 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-kp-9 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-ctrl-hotkey-kp-10 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-1 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-2 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-3 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-4 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-5 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-6 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-7 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-8 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-9 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-10 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-kp-1 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-kp-2 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-kp-3 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-kp-4 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-kp-5 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-kp-6 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-kp-7 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-kp-8 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-kp-9 "['']"
dconf write /org/gnome/shell/extensions/dash-to-panel/app-shift-hotkey-kp-10 "['']"
And then turn off and on the extension should make it work.