How to reset HomeKit?
Here's a solution from How To iSolve:


  Step 1: Go to “Settings”.
  
  Step 2: Open “Privacy” and tap on “HomeKit”.
  
  Step 3: There tap on “Reset HomeKit Configuration”.
  
  Step 4: Finally hit Confirmation Tab to finish the process.




However, I recommend reading the solution through, you might not even need to reset your HomeKit.