Welcome to FT. FYI you posted your question in the LAX thread of the Delta forum, where the UA forum may be better able to advise with UA connections at LAX specifically as it pertains to going from T7 to T6. I pinged the moderators to see if they want to move your post over.

However as a general rule there is no exit security when departing the US, and since your Kona flight is also arriving from the US, you will not need to go through customs at either KOA or LAX, nor should you need to pick up luggage if you are booked on a single ticket from KOA-LAX-YYZ. (Even if you are on separate UA tickets I suspect they would check it through for you but again that's a UA-specific detail)