Thanks ??
Concerning your question about mass action (like deleting more layers at once or removing them from a layer): this is planned for a future release for the backend. If you use phpmyadmin you can always directly edit more markers at once with SQL statements. The following statement for example will unassign all markers from layer ID 1 to layer ID 0 (= invisible layer containing all unassigned markers):
UPDATE wp_leafletmapsmarker_markers SET layer = 0 WHERE layer = 1
When you want to delete all markers from layer ID 0 instead of assigning any layer to these markers, you can do this on the layer edit screen by pressing the button “Delete layer AND all assigned markers” or use the following SQL statement:
DELETE FROM wp_leafletmapsmarker_markers WHERE layer = 1