The Request logs are managed by size in "/etc/ts/tools/asmlogd.cfg" and by row limit in "/etc/ts/tools/asmlogd_clean_db.yaml".
It sounds like the clean up may not have happened/be happening correctly to allow it to get to 4 million rows. This should be limited to 3000000 (3 million) rows.
To reduce the size of the requests you can reduce the size in the asmlogd.cfg and the row limit in the asmlogd_clean_db.yaml then reload ASM.
The steps in https://support.f5.com/csp/article/K11370 are for pre 11.6 when tables and storage management methods are changed.
The steps in https://support.f5.com/csp/article/K6992 will completely reset the ASM configuration not just log data.