❔ Im learning refs and outs

i keep getting cs0177 errors if someone could take a look

public static void RemoveAllHeroes(string name, out List<Hero> sub)
{
List<Hero> _heroRem = new List<Hero>();

for (int i = 0; i < _heroes.Count; i++)
{
if (_heroes[i].Name.StartsWith(name, StringComparison.OrdinalIgnoreCase))
{
_heroRem.Add(_heroes[i]);
_heroes.RemoveAt(i);
}
}
}