<div aura:id="error-toast-container" class="slds wr-toast-container wr-toast-container-format slds-hide" >
		<div aura:id="error-toast" class="slds-notify slds-notify_toast wr-toast-format" role="alert">
                <span aura:id="iconToast" class="slds-hide slds-icon_container slds-icon-utility-error slds-m-right_small slds-no-flex slds-align-top">
                    <lightning:icon iconName="utility:warning"/>
                </span>
			<div class="slds-notify__content">
				<h2 class="slds-text-heading_small">
					<lightning:formattedText value='{!v.errorMessage}'/>  
					<lightning:button aura:id="addLine" class="slds-hide wr-destructive-link-format" variant="" onclick="{!c.onReadMore}">{!$Label.c.ReadMore}</lightning:button> 
				</h2> 
			</div>
			<lightning:buttonIcon variant="bare" class="slds-notify__close slds-button_icon-inverse" title="Close" iconName="utility:close" onclick="{!c.closeToast}" size="large">
			</lightning:buttonIcon>
		</div>
	</div>

============================================================
Controller : 

onReadMore : function(component, event, helper){  
        $A.util.addClass(component.find('error-toast-container'), 'slds-hide');
    }