Session Drummer Issue

Please forgive me if this is a redundant question.  I am using Sonar 8.5 Producer with Windows 7 64 bit.  When using Session Drummer, if I inadvertently hit one of the lower keys, a drum riff will play.  Once it has been introduced to the mix, it will play this pre-programmed riff every time the play button is pressed, and there seems to be no way of getting rid of it.   Even if you delete the track, the sound still plays.  I have had this problem from time to time over the past few years, and have lost work over it.  Any ideas on how to get rid of the sound once it is introduced?   Thanks so much in advance.