If you have a child site which has post content and comments enabled, it is a fact of life that you will inevitably deal with spam comments.
Antispam Bee will add a setting section under Settings > Antispam Bee
You can find more information about Antispam Bee on their docs. There is a bulk setting key for Antispam Bee, which also means the number of days until existing spam is deleted can be easily set, using the MainWP Bulk Setting Manager extension.
You can bulk delete comments flagged as spam using a plugin like WP Optimize on the child site. Once the plugin has been installed, go to WP Optimize > Database
To run the optimization to delete spam comments and comments that have been trashed.
Advanced Database Cleaner
Another plugin option for bulk deleting spam and trashed comments is Advanced Database Cleaner.
Once the plugin has been installed and activated on the child site, go to the WP DB Cleaner admin menu;
Select spam comments and trash comments, then the clean button, and click apply.
Those same settings can be applied using this bulk settings key to clean spam and trash comments, using the Advanced Database Cleaner plugin.
You can also delete all comments marked as spam using a WP-CLI command;
A mix of these options will help in keeping your child site clean of spam comments.