Call Off
to cancel something that was planned, like an event or activity, usually because something changed or didn't go as expected.

Examples:
1 - They had to call off the outdoor picnic because of the heavy rain.
2 - The meeting was called off because the manager was not available.

Point:
1 - The teacher called off the test because many students were sick.
2 - The teacher called the test off because many students were sick.