All logs are there only for troubleshooting purposes mainly. They allow the history of what a software has done to be viewed. No ALM software generated logs are needed by the system unless they are still open and generating the latest history data, in which case they are locked by the system until they reach the size or time limitation at which point they are final written to the SA or QC log file folders. Deleting these logs will cause no harm but if needed for troubleshooting an issue that recently occurred you would want to keep a few of the latest ones. While the ALM system is writing a log file it is locked by the system against deleting and such until an action triggers it to close and a new file to be started. Once the file is released by the system it can be immediately deleted if one wants without harm, there will just be no history to review should an issue be discovered.
You mentioned the ALM db logs. Does this mean a log file within the DB itself and not within the ALM software log locations? These type of logs would be owned by the DB software itself (be it Oracle or Microsoft SQL) and be used solely for that software package. It would contain data that pertains to the DB itself. This type of log would possibly be protected by the application but that would be dependent upon how the DB admin set up that DB application. Usually it is a certain admin user that has the rights to delete those logs and they would be the one that would need to decide if those logs are needed and if all can be deleted or not. I have never accessed or used those logs, nor am I trained in them as they don't really pertain to ALM generally other than to show connection/communication issues and then we generally rely on the DB admin to manage those logs and assist in trouble shooting and getting that information for us. The DB itself is not anything we generally support or can offer assistance on other than the correct configuration of the necessary users and providing recommendations for the communication protocols used by ALM. If they are protected then you would either need to contact your DB admin to delete those logs or to use a user such as SA that has the necessary permissions delete such files. Support of DB software is generally outside of the scope of the ALM support contract, except for the support and recommendations stated previously.
I hope this helps.