Why the amazon river have a delta?

The Amazon River does not form a delta. Instead, it enters the Atlantic Ocean at a 200 km wide estuary.

A river delta is one or more distributaries of a river that flow into the ocean or another large body of water, such as a lake, where the river's decreased speed causes suspended particles to drop and thus build new land. The formation of a delta is driven by the interplay between the river's rate of flow, volume of water, sediment supply, wave action, and ocean currents at the river's mouth.

The Amazon River has too much water and too little sediment for a delta to form. The suspended sediment carried by the Amazon River is transported offshore and deposited on the ocean floor.

Furthermore, the Amazon experiences the highest tidal influence in the world's estuaries. The Amazon does not have a delta, so it is an anomalous river.