Before starting any work, you must shut off the water supply to the faucet. Locate the two shut-off valves under the sink, one for hot and one for cold. Turn the handles clockwise until they are fully closed. If you cannot find these valves or they are seized, you will need to shut off the main water supply to your house. Once the water is off, turn the faucet handle to the 'on' position to relieve any residual water pressure and drain the lines. Finally, place a thick towel or rag into the sink basin to protect the finish and block the drain.

Examine the faucet handle closely to find the set screw. Since we've assumed it's hidden by a decorative cap, look for a small, often plastic, cap on the front or top of the lever. It may have a small red/blue icon or a brand logo. Carefully use the tip of a utility knife or a small flathead screwdriver to gently pry this cap off. Underneath, you will find the set screw. This is typically a hex (Allen) screw or a Phillips head screw. Select the correct size Allen wrench or screwdriver and turn the screw counter-clockwise to loosen it. You do not need to remove it completely, just loosen it by several turns.

With the set screw loosened, the handle is likely fused to the valve stem by mineral deposits (lime and calcium) or corrosion. To break this bond, generously apply a penetrating solution. Spray a quality penetrating oil, like PB B'laster or WD-40 Specialist Penetrant, into the set screw hole and around the base of the handle where it meets the faucet body. For stubborn mineral buildup, a descaler is more effective. Soak a rag in white vinegar or a commercial product like CLR, wrap it tightly around the handle's base, and secure it with a rubber band. Let the chosen solution sit for at least 30-60 minutes; several hours may be needed for severe cases.

After letting the solution work, attempt to remove the handle. Grasp the handle firmly and try to wiggle it side-to-side and back-and-forth while pulling straight up. The goal is to break the final bits of corrosion free. If it remains stuck, introduce gentle heat. Use a hairdryer on a high heat setting and aim it at the base of the handle for 2-3 minutes. The heat will cause the handle metal to expand slightly, which can help break the seal. Be careful not to overheat any plastic components. After heating, attempt the wiggling and pulling motion again. You may need to repeat the cycle of applying penetrating oil, waiting, and gentle wiggling.

If the handle will not budge after all previous steps, the safest and most effective method is to use a dedicated Faucet Handle Puller. This tool is designed specifically for this task and prevents damage. A handle puller has two arms that hook under the base of the faucet handle and a central threaded rod that you position over the valve stem. As you tighten the T-handle on the central rod, it pushes down on the valve stem while the arms pull up evenly on the handle, popping it off without any wiggling or hammering. Position the puller, ensure the arms have a secure grip under the handle, and slowly turn the T-handle clockwise until the handle pops free.

Once the handle is off, take the opportunity to clean all the components. Use a wire brush or a stiff nylon utility brush to scrub the mineral deposits and corrosion from the inside of the faucet handle and from the exterior of the valve stem. A final wipe with the vinegar-soaked rag can help dissolve any remaining residue. This cleaning ensures the new or repaired handle will fit properly and will be easier to remove in the future. You can now proceed with your intended repair, such as replacing the faucet cartridge.