Not pretty sure that if am using it correctly but i was able to delete all the remote users. I just logged in to Remote site with admin priviledge and went to "Bulk User Action" searched for the user (remote), selected them and deleted them.
Not sure if it helps.
Moodle networking (MNet)
How to delete a remote user?
Энэ мэтгэлцээн түгжигдсэн тул та цаашид хариулт өгөх боломжгүй