Can I delete rows in oc_activity table where subject is "created_by"?

We are facing issue with Nextcloud postgres database is constantly using more disk space. The oc_activity table seems to have to many entries for subject “created_by”. It seems for each “created_self” event multiple “created_by” entries are created for other adin users. In order to free up the space we want archive the “created_by” records to a file and delete them. Is it ok to do that? Please advise.

Thanks in advance.