str:<span>@str</span><br>

<TagsInput @ref="tinput" @bind-Value="str" Options="opts"></TagsInput><br>
<Button Color="Color.Primary" @onclick="clear">Clear</Button>

@code{

    string str = "aa,bb";
    TagsInput tinput;
    TagsInputOptions opts = new() {MaxTags = 5,
        Source=new []{"aa","bb","cc","dd","eee","ff"},
        Removable =true};

    void clear()
    {
        tinput.Flush(); //or tinput.RemoveAll();
    }
}