Please accept my apology.
For large leaners the prescribed way to fell them is using a bore cut. Start by cutting a small scarf. Then, while staying well back from your hinge wood make a bore (plunge) cut into the middle of the tree. DON'T start the bore cut with the tip of your saw or it will kick back wildly! See this done before trying it! Don't cut the back side (tension side) of the lean, leave at least a couple inches of wood intact back there. Once you have a bore cut through the trunk carefully run that cut forward toward your scarf until your desired hinge thickness is reached. That remaining tension wood at the back of the lean is now your 'trigger wood'. Cutting that will let the tree go all at once without kicking back (barber chairing).
Please don't anyone try this without an experienced feller with you.
Some guys will modify the bore cut method to make an even safer stepped trunk cut with a lock left in place to prevent any barber chairing. Here's a decent video of that.
But on smaller leaners like 10" or less you just don't have enough wood to use the bore cut method. There's a safe way to fell these. Back in 2012 while I was working for the local Dept. of Natural Resources we had a massive late winter ice storm. We had 1000's of downed trees and leaners on our road and trail systems. I used this method many times that year.
You start by making a very shallow very wide scarf cut on the underside of the lean. It should be like 1/2" deep and 8" tall. Maybe a 135° angle - very wide. Slowly skim off 1/2" layers from this scarf, top and bottom with your chainsaw keeping the 135° angle. Once you get back close to the center of the stump start watching for motion and stop cutting at the first sign of it. If the tree is slowing leaning over than just step back and in a minute or 2 it will slowly lower itself to the ground very gradually and safely. If the tree stops moving when you stop cutting that means you're doing a real good job of watching for that first motion. You may need to take another shallow pass or 2 out of your scarf before it starts moving again. When that happens back away. It will come down now.
I don't suggest anyone try this alone. See it demonstrated first. Then practice on some small leaners until you can consistently make them take at least 60 seconds to fall after first motion. Don't think of it as tree felling but more like chainsaw carving. See how little you can take in a pass and see how the tree reacts.