For this example I used SQL Server 2008 R2. I configured the Backup BizTalk Server (BizTalkMgmtDb) job to make backups to the following locations:
F:\backup\full
F:\backup\log

Open SQL Server Management Studio and connect to your instance where the BizTalk databases are running. Open Management and right-click Maintenance Plans and click Maintenance Plan Wizard.

Click on Next

Give your maintenance plan a name. I used Remove old backups. Click on change to set up a schedule.

In this example I set the maintenance plan up to run daily. This does not mean that all files older than a day will be deleted. We will get to that later. This just means that the maintenance plan will run daily. If you set your schedule click OK.

Click in Next.

Select Maintenance Cleanup Task and click on Next.

Click on Next.

Select the folder where your backups are written to. In this example that folder is F:\backup. I selected Include first-level subfolders because the actual backups are written to F:\backup\full and F:\backup\log. The file extension of my backup files is bak. This is the default. In this example I want files older than a day old to be removed. This is what I normally do on development and test servers, because there is no real need to backup data. On production servers I also normally choose one day. Not that data is not important on production servers, but mostly a backup of the server is made during the night.

Choose if you want to have a text report or a report mailed and click on Next.

Click on Finish for the maintenance plan to be created.

Your maintenance plan should now correctly be created. Click on Close.

 This is just one of those steps that makes the life of an admin easier and frees up some time for more important issues.