NOTE: This article also applies to the Wemo Mini and Wemo Bridge.
Step 1:  Launch the Wemo app.
           
Step 2: Tap Rules.
 
Step 2: Tap Rules.

Step 3:  Tap a Currently Active rule under the ENABLED RULES.
 

Step 4:  On the upper-right corner, tap on Disable.
 

Step 5: Tap < Back to return to the Rules tab.

You should now have successfully disabled a rule on your Wemo app. Additionally, you may choose to Delete a rule to avoid conflicts with the Apple Home app. To learn how, click here.
Related Article:
Getting to know the Wemo Rules