In most situations it is best to set up a recovery point set limit in the backup job so that it keeps track of and deletes old backup sets automatically. It should be noted that when you do this, you need to have enough room for an additional full backup in addition to the number of backup sets you are having it save.
For instance, if you have it set to save 3 sets, and have it start a new set every week, you need enough space for 3 weeks worth of baselines + incrementals + an additional baseline. After it creates that 4th baseline it will delete the oldest baseline and all incrementals attached to it.
