Deleting existing Spambot accounts

I’ve taken over an existing website that has over 120k users, most of which are spambots.

I’m looking for info, discussions etc on ways to get rid of these already existing accounts.

One question though, is it okay to delete these accounts from the user table alone? or are there additional tables the ref these accounts.

in other words would this mess up the db to do that?

For example i was considering deleting all accounts w/ email addresses the end in .ru

any help on this topic would be appreciated, thanks

Drupal version: