Remove and modify the items in panels of Linux desktop is a common problem in Internet cafe's and libraries. A solution is available with Xubuntu Linux to prevent removing the items from desktop panel accidentally by users.
Follow the steps below,
1. Configure the panels before start the process. Add/remove/edit items from panels.
2. Apply the following command,
sudo cp /home/vimal/.config/xfce4/xfconf/xfce-perchannel-xml/xfce4-panel.xml /etc/xdg/xfce4/xfconf/xfce-perchannel-xml/
3. Apply the following command to edit the file.
sudo leafpad /etc/xdg/xfce4/xfconf/xfce-perchannel-xml/xfce4-panel.xml
4. Find following line at the top of the file.
<channel name="xfce4-panel" version="1.0">
Insert # symbol at the start of the line.
5. Copy the following line and paste after the line above mentioned line.
<channel name="xfce4-panel" version="1.0" locked="*" unlocked="root">
Save the file.
6. Restart your system.