Hi @marxmann,
It might be worth checking that permissions on this folder are 755 with an owner of www-root on the wp-content/wflogs folder, just in case there are problems maintaining the file. If you have no choice but deleting the files inside that folder, Wordfence should simply create a new one within 30 minutes.
If this file growing to a large size is a persistent problem, you could always try the WAF’s MySQLi storage engine, to avoid needing to write to the wflogs folder at all: https://www.wordfence.com/help/firewall/mysqli-storage-engine/
Let me know how you get on!
Peter.
