Can you turn off those task notifications? No...and the reason is:
strake/IR was designed for incident response, including the automation of some pretty important processes that involve many people on one or more team. Hence, those notifications need to be sent in order to ensure folks know what they are supposed to do when.
HOWEVER...you do not necessarily need to receive them if you have determined a use case that does not require email notifications. This involves addressing the strake/IR email in your email client filter.
Reasons you might not want notifications? You are testing or using your processes in place and don't need notification of when to perform your tasks...You are a lead process designer or process improvement guru and, again, are working strictly within strake/IR.
WHAT TO DO? We recommend you use your mail client filter to place strake/IR emails into a specific folder and choose how your client should handle them. We will occasionally send you emails from outside of the solution and we'd suggest you allow those through. We may be sending product update or service information to you that you will want to read!
Here are a few helpful links to the most popular mail clients to help you do this.