In early 2018, the ability to delete logs from the database was removed from iThemes Security, now known as Kadence Security. This plugin gives you that control back.
Works with Kadence Security, plus older versions released as Solid Security and iThemes Security.
Log cleaner for Kadence Security Support at the official WordPress repository.
Note: This plugin comes with no warranty of any kind.
Deactivate the plugin, delete if desired.