Hello,
One of my customers got a Magento 2.0 website and they recenty got more than 300 000 spam registrations. I am going to be banning chinese and russian ip adresses but first of all I wanted to ask help from guys for a way to remove customers (mass delete).
I have tried removing the customers by selecting multiple customers but I get a blank page when I do so an get this error in Apache2s error_log file:
[client 178.63.87.197:54474] [client 178.63.87.197] ModSecurity: collections_remove_stale: Failed to access DBM file "/var/mod_security/secdata/ip": Permission denied [hostname "www.naturalscents.ca"] [uri "/cgi-sys/ea-php70/index.php"] [unique_id "W8pgyqB@tMFDdR20y
Is there a way for you guys to tell me :
1- How I can enable debugging messages to know more about the problem I experience when I get a blank page
2- If its possible to tell me if this Mod_Security could be causing the problem and if so, how I can fix it
3. (Which is one of the most important point) Can you guys tell me how I can mass delete customers from the database directly. Like... lets say delete the customers 10 001 to 15 000 in a simple command if possible.
The problem is that mixed up in the 300 000 customers there are real customers. But there are so many registrations that I can delete blocks of 1000-2000 customers from the database if I knew how to do it from MySQL.
My customer is desperate and so do I.
Please help if possible 
this is kinda urgent ....
I really appreciate guys,
Best regards,
J Lachance