If you don't know what addon folders you can safely delete,
Minion is your best friend.
But the message about LUA running out of memory does not directly have to do with that.
It's just telling you that your addons are using more memory at the same time than ZoS expected.
You can modify the UserSettings.txt file in your Documents\Elder Scrolls Online\live folder and safely change
Code:
SET LuaMemoryLimitMB "32"
to 64 or 128 to avoid this message.