The omnipotence paradox is a seemingly tricky issue. Can God do something contradictory, like create a thing too heavy for Him to lift, too thick for Him to see into, too complex for Him to understand, too powerful for Him to defeat, etc? If the answer is yes, there is something more powerful than God, but if the answer is no, He is unable to do something. Either way, God is, supposedly, not omnipotent.
Interestingly, the Bible says there are several things God cannot do. He cannot, for example, lie (Hebrews 6:18). So is God really omnipotent? Yes, because the limits on His power aren't coming from an external force. His limits are coming from God Himself. It is impossible for God to lie because God isn't a liar. It is impossible for God to limit His knowledge because God is omniscient. It is impossible for Him to create a being too powerful for Him to defeat because He is sovereign. Every limit on God is God.
Omnipotence, when correctly understood, isn't the ability to do the logically incoherent, but to not be limited by any external factors. You, as a human, can set limits on yourself, but you cannot defend against limits imposed on you. But God cannot be limited by anything that isn't God. Therefore, while there are things God cannot do, it is still entirely legitimate to say He is sovereign over all things. Therefore, God is fully omnipotent.