My observations suggest that you can only add a maintenance cleanup task (to delete expired backups) from the machine on which SQL Server resides. When I run the maintenance plan wizard from SSMS on my own machine, I don’t get that option.
Once you successfully add a maintenance cleanup task, how do you get it to delete .bak, .dif and .trn files all in the same task? Leaving the extension box blank doesn’t result in anything getting deleted. The secret is to enter * as the extension. The period before the extension should be omitted.