TextArea highlighted as touched after marking control as unt

It looks like there are some problems with textarea validation styles. We will fix that in the next version of MDB Angular (which should be relased next week). You can add those styles to your global styles.scss file as a workaround for now:

.md-textarea.validate-success.ng-valid.ng-untouched.ng-pristine {
    border-bottom: 1px solid #ced4da !important;
    box-shadow: none !important;
}

.md-textarea.validate-success.ng-valid.ng-untouched.ng-pristine + label {
    color: #757575 !important;
}

.md-textarea.validate-success.ng-valid.ng-dirty,
.md-textarea.validate-success.ng-valid.ng-touched {
  border-bottom: 1px solid #00c851 !important;
  box-shadow: 0 1px 0 0 #00c851 !important;
}

.md-textarea.validate-success.ng-valid.ng-dirty + label,
.md-textarea.validate-success.ng-valid.ng-touched + label {
  color: #00c851 !important;
}

If your controls have values and you mark them as untouched, they are still marked as dirty and the validation styles will be applied for this state. If you want to reset validation styles completely, you need to mark the controls as untouched and pristine (or just reset them).

It's also possible to remove success or error validation with [validateSuccess]="false" and [validateError]="false" inputs.