Can't delete timeline variable

Development Programming & Scripting Blueprint
,
1

Add a Timeline, and then remove the newly added timeline node using “RemoveUnusedNodes” in the editor tool. The Timeline variable in the blueprint cannot be removed now.

2

Use this to clear the invalid timeline

void UEditorToolFunctionLibrary::RemoveInvalidTimeline(UBlueprint* Blueprint)
{
	Blueprint->Modify();
	int32 removedNumber = 0;
	
	TArray<TObjectPtr<class UTimelineTemplate>> deleteTimelines;
	for (auto timeLine: Blueprint->Timelines)
	{
		UK2Node_Timeline* TimelineNode = FBlueprintEditorUtils::FindNodeForTimeline(Blueprint, timeLine);
		if (!TimelineNode)
		{
			deleteTimelines.Add(timeLine);
			removedNumber++;
		}
	}
	for (auto deTimeLine : deleteTimelines)
	{
		deTimeLine->Modify();

		Blueprint->Timelines.Remove(deTimeLine);
		deTimeLine->MarkAsGarbage();
	}
	deleteTimelines.Empty();

	if (removedNumber>0)
	{
		FBlueprintEditorUtils::MarkBlueprintAsStructurallyModified(Blueprint);
	}

	UE_LOG(LogTemp, Log, TEXT(" --- Removed timelines number: %d "),removedNumber);
}
3

If you are looking for a solution for 4.27, here it is. And don’t forget to add module UnrealEd in public dependencies

void UV_BlueprintFnLibrary::RemoveInvalidTimeline(UBlueprint* Blueprint)
{
Blueprint->Modify();
int32 removedNumber = 0;

TArray<TSoftObjectPtr<class UTimelineTemplate>> deleteTimelines;
for (auto timeLine: Blueprint->Timelines)
{
	UK2Node_Timeline* TimelineNode = FBlueprintEditorUtils::FindNodeForTimeline(Blueprint, timeLine);
	if (!TimelineNode)
	{
		deleteTimelines.Add(timeLine);
		removedNumber++;
	}
}
for (auto deTimeLine : deleteTimelines)
{
	deTimeLine->Modify();

	Blueprint->Timelines.Remove(deTimeLine.Get());
	deTimeLine->MarkPendingKill();
}
deleteTimelines.Empty();

if (removedNumber>0)
{
	FBlueprintEditorUtils::MarkBlueprintAsStructurallyModified(Blueprint);
}

UE_LOG(LogTemp, Log, TEXT(" --- Removed timelines number: %d "),removedNumber);

}