When your database has grown too large you can free up space by performing a clean up. An administrator or project manager can perform such a clean up. The file menu of the administrator contains the project item Clean up. This item is active when a project is selected. It opens the dialog Clean up in which you can choose to either remove unassigned labels or document revisions. These revisions can be selected on age or on their major revision number. A clean up does not delete the items permanently yet, but the items are marked for deletion. This means that they can be restored after a clean up. To free up the space and delete the items permanently a Purge action (to be executed by an administrator) has to be performed.
Remember to back up your data before performing a clean up.