Cut spaghetti squash lengthwise and scoop out the seeds.
Open the Instant Pot and add 1 cup of water.
Stack the spaghetti squash on top of each other, cut-side up.
Close the lid and make sure the vent on the top of the lid is closed.
Set to manual, high-pressure for 5 minutes.
When the timer goes off, turn the vent on the top of the lid to release the steam.
Wait about 5 minutes for the steam and pressure to dissipate.
Open the lid and test the spaghetti squash. Fork to turn squash into spaghetti-like noodles. Take a bite to test that it's done. You can always cook for another 1-2 minutes on high pressure if needed.