clarification betwin options with different outcomes

There are two functions with the same naming but sligtly different outcome,
which may cause unintended user confusion and usage of wrong option
not in accordance to user expectations.

These options are
*Delete module and its files - where outcomes are 'permanent lose of part Advanced Sidebox functionalities which was provided by deleted addon files.
*Delete box - which unpublish box from user view and remove its instance.

Actions taken
* Delete files message has been adjusted to suggest less invasive option,
and inform user about consequences in case of continuing.
* Delete box instance, naming has been changed from Delete to Remove to distinguish
from Delete function.