One of the stock SQL Server Agent jobs added when replication is installed is the Distribution clean up task. Once all subscribers have received replicated transactions, the sp_MSdistribution_cleanup stored procedure is called to remove delivered transactions from the distribution database. The amount of time delivered transactions remain in the distribution database is known as the retention period and defaults to 72 hours for transactional replication. You can change the retention period for a distributor by following these steps.
Right-click the Replication node in Enterprise Manager on the distributor and select Configure Publishing, Subscribers, and Distribution from the menu.
On the Distributor tab, select the distribution ...