you can judge by the value of these two input. If both value are not empty, let the disabled attribute of button be false, otherwise true

<input [(ngModel)]="name" (ngModelChange)="onchange()"/>
<input [(ngModel)]="pwd" (ngModelChange)="onchange()"/>
<button [disable]="isDisable" (click)="onLogin()"></button>

isDisable=true;
name='';
pwd='';
onchange(){
    if(name.length>0&&pwd.length>0){
        this.isDisable=false;
    }else{
        this.isDisable=true;
    }
}

style when writing CSS to control whether Button is available