The user needs to be able to delete a Database Collection if it was created by mistake or it is not needed anymore, it is really important to add this feature as soon as possible since Wordpress and other Competitors allow these type of actions.
Wix’s stance on this will be that it has the potential to create a huge amount of issues with un-skilled users accidentally deleting their collections. I would suspect this is why they have engineered the platform so that collections are never truly deleted and instead hidden. A happy compromise would be that when a collection is hidden it can not be simply restored by the user creating a collection with the same name again, instead it would have to be restored by a member of the wix team.
This way Wix don’t have a huge amount of issues with un-skilled users (of which they have many) accidentally permanently deleting their collections, and you get what you want, kinda 