A sticky iron is usually caused by a dirty soleplate. Fabric or plastic from clothes might get stuck on it or lime might build up over time. See if the following will solve the problem.
Clean the soleplate
For milder cases, try wiping the soleplate with a wet rag dipped in water or vinegar and wring out the excess water. You may add a few drops of dish soap to the water. Set your iron to the lowest temperature and let it warm up. Unplug the appliance and scrub the soleplate with the damp rag to get rid of gunk or limescale. Take care not to touch the soleplate with bare hands. Let it dry before using your iron again.
If that’s not effective, set your iron to the maximum temperature and let it heat up. Turn of the steam function and slide it over a piece of paper or paper towels to remove gunk or limescale.
Do not use abrasive items or cleaning products
Abrasive detergents or items like metal scouring pads or steel wool will wear out your iron’s soleplate and might cause scratches. Avoid using these on your iron.