If you have separate kitchen taps for hot and cold and they are not a mixer or combined tap, then switch on your cold water. If you have airlock, no water will come out. In the kitchen only, you may consider using a short length of hose to connect the cold and hot taps before switching on the hot tap. As the water flows out of the hot tap and into the cold tap, the hot water is pushed through the cold water system and should force the airlock back into the water tank.
If the kitchen tap is a mixer, you should switch on the cold tap. Then, with a cloth, you should block the mixer tap while you switch the hot tap on gently.
Whichever way you have carried out the first step, you should leave your method of airlock clearing running for one or two minutes, switch off the hot tap and leave the cold water running for a couple of minutes to check the problem has been resolved. If the method hasn’t been successful and you still have an airlock in your cold water system, then it is worth considering calling in a plumber to try and fix it.