As you've read, Uranus was afraid of his children, the Hecatoncheires and the Cyclopes, and imprisoned them in Tartarus. His relationship with the Titans was also one of fear and conflict.

Uranus loved ruling the universe and feared anything that threatened his power — and he viewed his children as such threats. Therefore, he also decided to keep the Titans out of the way. Instead of imprisoning the Titans, however, Uranus tried to prevent them from being born by shoving each child back into Gaia's womb. He did this to all twelve of these children. Uranus, pleased with himself, was able to relax because he believed that his power was no longer threatened.

Not surprisingly, Gaia was unhappy with the pain inflicted upon her and with her children's predicament. She decided to take action against Uranus. Gaia made a sharp sickle out of either iron or flint and complained to her children, suggesting they rise up and punish Uranus for his mistreatment of the whole family. Afraid of their father, the Titans and Titanesses refused their mother's request. Gaia, however, did not give up. She kept complaining and cajoling until Cronus, the youngest Titan, agreed to get revenge upon Uranus. Gaia smiled upon this favored son and told him her plan.

Cronus lay in wait that night, armed with the sickle his mother had made. Uranus began to make love to Gaia. Cronus, wasting no time, grabbed his father's genitals and sliced them off with the sickle. He tossed the severed organ from the heavens into the sea.

After this incident, Uranus seems to drop out of the picture. He was no longer worshiped or honored with sacrifice, and he held no power.