Why does Parris hate Proctor?
In my opinion, Parris hates John Proctor because Proctor opposes his efforts to make himself more important.
Parris is very interested in increasing the prestige of his office (that of the minister for the town) and, thereby, his own prestige. But Proctor has opposed these efforts. He has, for example, opposed the efforts to have fancy candlesticks for the altar of the church. Parris sees this opposition as an attack on him personally.
So Proctor makes Parris hate him by opposing Parris's attempts to make himself seem more important.