Is there a way to delete/clean up the call logs?

Yes you can delete call logs using the API by sending a delete request to the logs or call endpoint with the appropriate call Id Visit here for more guide https://docs.vapi.ai/api-reference/logs/logging-controller-logs-delete-query

Why can't I just select it and delete it? Why make it complicated with APIs, especially for none developers?

if you would like to suggest that feature, i think that would be helpful for others as well. you can suggest it here: