At first, I found them to be very "clingy" as others have described them but as it turns out, it's very simple.
Slide the slide lock in to lock and slide it out to unlock. This may seem very simple and obvious but it fooled me initially and I was having a tough time getting the straps on and off at first. Turns out just slide the lock OUTWARD and sliding the strap on and off should be much easier. Hopefully I can help prevent people damaging their joycons.