The stage tables are not cube data so will not impact data in your application if you remove but will impact the ability to drill down. Therefore you may only want to retain the stage data for a period which it may be used e.g. the last 12 months. Similarly the Error Logs in OneStream can grow to a significant size depending on the level of debugging you have built into the application. This can be managed from the Error Log screen in the System tab which allows you to delete all records older than 30 days or you can set up a custom job schedule to manage this. It is also advisable in any Production application to ensure that the logging level is set to the lowest level necessary i.e. not Debug