Where's the button Restart

I was doing an animation when krita told me i needed more space so i went to the place where the button restart should be but i didn’t find it anywhere.
Please help me

You don’t need buttons for that, you can use krunner…

Alt>Space type: logout or reboot

Right here:

Restarting the system probably won’t save you any space though. You might try using the Filelight app to find big things you don’t need that can be deleted.