Cinnamon cannot disable or remove window decorations, according to this issue on GitHub. The option to remove window decoration is yet to be implemented.
User may instead use any of the workarounds as follows.
Workaround 1 (easy)
Use the smallest font size for window title. Go to System Settings > Appearance - Fonts. Then under Font Selection - Window title font: change the font size from the default 10 to the smallest value 1, then click Select to finish.
Assuming the screenshot is pixel-perfect regardless of screen resolution, the height of window decoration was reduced by: 14 pixels in Cinnamon 2.2; 17 pixels in Cinnamon 3.8.
Window decoration in Cinnamon seems to use Metacity theme with Mutter/Muffin support; traditional themes do not seem to work. Different combination of themes for window borders and controls may affect the result. Some themes do not reduce the height of window decoration as much as other themes. For example, Mint-Y had worse result than Mint-X.
Limitation: This workaround is theme dependent. Known themes that work well with this workaround are very few: Mint-X, BlueMenta, Greybird.
Workaround 2
Use any utility tool like Devil's Pie or Devilspie2, which can remove window decorations for EWMH-compliant window managers. This will require user configuration to remove window decoration.
For Devilspie2, open a text editor and type the following code.
if (get_window_type()=="WINDOW_TYPE_NORMAL") then
undecorate_window();
end
Save as file in $HOME/.config/devilspie2 with any name followed by .lua in the filename. Run devilspie2 to see the result. To make the changes persistent at reboot, add the command devilspie2 to Settings > Preferences - Startup Applications.
With above configuration, all running applications with normal window type will have no window decoration at all. This related post has my answer with details on how to use Devil's Pie and Devilspie2 to remove window decoration by application name instead.
Limitation: This workaround will not work against applications with the client-side decoration a.k.a header bar in GNOME; thus modifying the theme may be the only alternative.
Workaround 3
Modify the theme. Cinnamon window manager, Muffin, supports Xfwm4 and Metacity themes for its window decorations: check /usr/share/themes/THEMENAME directory and look for either metacity-1 or xfwm4 subdirectory.
This answer on Ask Ubuntu had suggested to edit the XML file of the currently used theme:
[...] You can edit
/usr/share/themes/Mint-X/metacity-1
and set all non-zero value properties in the metacity-theme-1.xml (of course you need sudo, to edit something there. A backup is useful.) [...]
The filename may vary depending on which theme in use.
Perhaps theme modification is the only "reliable" way to remove window decoration. The known limitations in other two workarounds seem redundant, except this is a tedious workaround.
Disclaimer: I don't use Cinnamon on daily basis and just explored again recently for experience. I did not verify the third workaround because that will take some time to test.
Tested with Cinnamon 2.2 in Linux Mint 17 (Live) and Cinnamon 3.8 in Linux Mint Debian Edition 3.
Best Answer
try
kwin --replaceorDISPLAY=:0 kwin --replaceif you're not in X.Source