Hi together,
just want to share my experience with the uninstall of the ldap-plugin.
First i tried to uninstall the plugin inside the webgui.
Uninstall did work but the entry in the menu was still there. A click on the menu opened the config side but with an erromessage "RDP ldap is missing". Don't exactly remember the message.
So i searched in the forum but didn't find anything compare to my problem.
while waiting for grand access to the forum i find the solution on my one 
Trick was to not uninstall the plugin in the webgui.
Just open an ssh terminal and execute the following comand "sudo apt-get remove --auto-remove --purge openmediavault-ldap".
That did the job and makes a fully remove of the package and all the installd dependencies and also delets the entry in the menu in the webgui 
Maybe this will helb someone else 
Cheers
Sascha