Why Can Amon Take Bending Away?

He also claimed that he had been granted the power to remove bending by the spirits because they believed the Avatar had failed the world and wanted him to usher in an era of equality.

Why Amon can take bending?

Amon created a way to take away a bender's bending by disrupting the chi flowing through their body, and this is likely thanks to his knowledge of chi blocking, as well as his bloodbending.

Why is Amon immune to Bloodbending?

As with most kinds of bending, most bloodbenders need to perform certain body movements in order to bend the blood. But Amon is able to use psychic bloodbending, which allows him to bend without any motions. This is how he tricks his followers into believing he can remove bending without being a bender himself.