Can't free space after uninstalling plugins

I am using OpenAtv 6.3 and i notice whenever I try to uninstall a plugin, there is a lot of space wasted after uninstalling the plugin. For example I tried to download Kodi 18 from the plugin menu and my free space was 303 MB after installing it became 174. However, after uninstalling it my free space is now 235 MB. Is there a way to completely uninstall a plugin via a command or something ? I would really appreciate your help.