Why did spider man get rid of the black suit?

Because He realized that the longer he kept the black suit the more it took over him and made him more aggressive, murderous, angry, etc. and not wanting to be like that or actually kill the crooks he catches he tears it off with the help of the church bell. However in an alternate version "marvel adventures Spider-Man" he gets rid of it because it's feeding off of his superhuman abilities, and the Symbiote also comes off of him willingly.