shadows/framework/src/main/java/org/robolectric/shadows/ShadowPackageManager.java
@Nullable
  public ActivityInfo removeActivity(ComponentName componentName) {
    return removeComponent(
        componentName, activityFilters, p -> p.activities, (p, a) -> p.activities = a);
  }
@Nullable
  public ActivityInfo removeActivity(ComponentName componentName) {
    return removeComponent(
        componentName, activityFilters, p -> p.activities, (p, a) -> p.activities = a);
  }
Removes activity from the package manager.

@return the removed component or {@code null} if no such component existed.