Question

how can federal judges be removed from their positions?
○ by popular vote
○ by the supreme court
○ through recall by state governors
○ through impeachment by congress

Explanation:

Federal judges in the US can be removed from their positions through impeachment by Congress. Popular vote doesn't remove them, the Supreme Court doesn't remove federal judges (it's a separate branch), and state governors have no authority over federal judges.

Answer:

through impeachment by Congress