1. Quit the "Terminal" application and relaunch it, to make sure that you are NOT logged in as another user (root for example). This is important, because the folder we create will get all the permissions from the parent folder (your "home" folder), and only the user who created the new ".Trash" directory (you) will be able to use it without restrictions.
2. In the Terminal type
sudo rm -frv ~/.Trash
to remove the old ".Trash" directory and all folders and files in the old ".Trash" directory.
3. In the Terminal type
mkdir -v ~/.Trash
to create a new ".Trash" directory in your "home" folder!
4. In the Terminal type
osascript -e 'tell application "Finder" to quit'
then
osascript -e 'tell application "Finder" to activate'
to restart the Finder!
5. Done! You can now move files in the trash!
If the Finder restart does not work on your system, then logout/login to activate the new trash can.