If you happen to discover a directory which for some reason happens to be called '~' please do not and I repeat do not try to delete it by running the  'rm -rf ~' command.

Oops.

The correct (safest) way to do this is to fire up Nautilus file manager and remove the file via the graphical interface.

Next time make sure that you've made a recent backup of your home directory in case disaster strikes again.