To get red of the Software Manager icon in the menu, do the following. Update mint-lxde-default-settings to version 12.0.11.
sudo apt update
sudo apt upgrade
For existing users, you have to copy the .config file in /etc/skel into the user´s home folder. If you do it for yourself, it has to be done like this:
cp -r /etc/skel/.config ~
Logout and login and you will see that the non-working Software Manager icon has disappeared.
When new users are created, this icon will not be shown anymore.