Where to connect unused pins operational amplifier
It's good practice to tie them somewhere.
If you can spare a couple of resistors, it's good to connect the non-inverting input to a defined voltage (like ground, or a rail) with a series resistor, and connect the output to the inverting input with a resistor, to make a voltage follower.
If you just connect the output to the -ve input, and the +ve to ground, then later you suddenly find a use for the amplifier, you may be stymied by the hard connections. You can remove resistors and use their pads as the connections to your new function.
If you're certain you're not going to want to use the other amp ever, then don't use the resistors. However, I've been electrical engineering for my living for 40 years, and I've never yet had a board enter production the same way it left design!