Not sure if you still have the problem but it should not be that difficult. If you foe download Iobit uninstaller and let it do the job it will clear out bluestacks in program and in programdata. after this you will be asked for a deep clean for left-overs (registry etc). If you already took away parts it might not work. Then clean manually in program and in program data. search in registry and in general for bluestacks.
hope it works!