void remove(DataType dt) {
		boolean notify = false;
		if (isRecentlyUsedDataType(dt)) {
			recentlyUsedDataType = null;
			notify = true;
		}
		if (notify) {
			notifyListeners();
		}
	}
Data type was removed, so remove it is no longer a recently used.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/datamgr/DataTypePropertyManager.java