ionic2 remove blue line color input md

Here is another version, without !imporant keyword:

 ion-content {
    %no-input-border {
      border-bottom-color: transparent;
      box-shadow: none;
    }

    ion-item {
      &.item-input {
        &.item-md {
          &.input-has-focus {
            .item-inner {
              @extend %no-input-border;
            }
          }
        }

        &.ng-invalid {
          &.item-md {
            &.ng-touched:not(.input-has-focus):not(.item-input-has-focus) {
              .item-inner {
                @extend %no-input-border;
              }
            }
          }
        }

        &.ng-valid {
          &.item-md {
            &.input-has-value:not(.input-has-focus):not(.item-input-has-focus) {
              .item-inner {
                @extend %no-input-border;
              }
            }
          }
        }
      }

try using the following code:

.item-md.item-input.input-has-focus .item-inner {
  border-bottom-color: transparent !important;
  box-shadow: none !important;
}

.list-md .item-input.input-has-focus:last-child {
  border-bottom-color: transparent !important;
  box-shadow: none !important;
}

.list-md .item-input.input-has-focus:last-child .item-inner {
  box-shadow: none;
}

.item-md.item-input.ng-valid.input-has-value:not(.input-has-focus) .item-inner {
  border-bottom-color: transparent !important;
  box-shadow: none !important;
}

.list-md .item-input.ng-valid.input-has-value:not(.input-has-focus):last-child {
  border-bottom-color: transparent !important;
  box-shadow: none !important;
}

.list-md .item-input.ng-valid.input-has-value:not(.input-has-focus):last-child .item-inner {
  box-shadow: none;
}

.item-md.item-input.ng-invalid.ng-touched:not(.input-has-focus) .item-inner {
  border-bottom-color: transparent !important;
  box-shadow: none !important;
}

.list-md .item-input.ng-invalid.ng-touched:not(.input-has-focus):last-child {
  border-bottom-color: transparent !important;
  box-shadow: none !important;
}

it'll remove all validation lines (red/green/blue).

EDIT

There's a better way for doing this using theming.

Go to your theme.scss file inside src/theme and use this code

$text-input-md-highlight-color-invalid: transparent;
$text-input-md-highlight-color-valid: transparent;
$text-input-md-show-invalid-highlight: transparent;
$text-input-md-highlight-color: transparent;
$text-input-md-show-valid-highlight: transparent;